Basic Electronics Courses Flashcards
What is the fundamental principle of capacitance in electronics?
Capacitance is the ability of a device to store electrical energy.
How does a capacitor differ from a storage cell like a battery in terms of current and time?
A capacitor delivers a large amount of current over a short period while a storage cell provides a small amount of current over a long period.
What physical structure defines a capacitor?
Two conductors separated by an insulator (dielectric).
What is ‘stray capacitance’ and why is it significant in electronics?
Stray capacitance is unintended capacitance between conductors separated by an insulator which engineers must manage in circuit design.
What is the key difference between the electrostatic field in capacitors and the electromagnetic field in inductors?
Capacitors operate with an electrostatic field while inductors operate with an electromagnetic field.
What does the letter ‘C’ represent in electronic schematics?
The letter ‘C’ represents a capacitor.
How can the capacitance of a variable capacitor be adjusted?
By varying the distance between the plates or by meshing the plates closer or farther apart without touching.
Why should you never touch both leads of a capacitor with your hands?
Because capacitors can hold a charge that may be lethal if discharged through the body.
What is the basic unit of capacitance and how is it defined?
The farad; it is the capacitance that stores one coulomb of charge at one volt.
What are the common subunits of capacitance used in electronics?
Microfarad (μF 10⁻⁶ farads) and picofarad (pF 10⁻¹² farads).
Why was the term ‘nanofarad’ historically avoided in capacitor labeling?
Because manufacturers preferred terms like ‘mil-microfarad’ or expressed values in picofarads possibly due to confusion over the letter ‘n’.
What safety concern is associated with large capacitors in circuits?
They can store lethal amounts of energy and discharge suddenly posing a risk of electric shock or death.
How long can a perfect capacitor theoretically hold a charge?
Indefinitely if it has no discharge path and no manufacturing defects.
What is the role of the dielectric in a capacitor?
It acts as an insulator separating the two conductive plates allowing the capacitor to store charge.
How do engineers deal with stray capacitance in advanced circuit design?
By identifying and minimizing it to prevent unwanted effects on circuit performance.
What happens when a magnetic field passes through a conductor?
It induces an electric current in the conductor.
Why are modern integrated circuits vulnerable to electromagnetic pulses (EMPs)?
Because they operate with minute amounts of current and EMPs induce currents that can fry these circuits.
What is the potential impact of a high-altitude nuclear explosion on modern electronics?
It can generate an EMP that disables electronics over a wide area potentially sending society back technologically.
Why do old diesel engines continue to work after an EMP event while modern vehicles may not?
Because old diesel engines use mechanical compression ignition without electronic controls unlike modern vehicles with computer systems.
What is the purpose of magnetic shielding in military applications like Air Force One?
To harden electronic systems against EMP-induced currents and electromagnetic interference.
What technology did the Airbus A320 introduce that made it vulnerable to electromagnetic interference?
Fly-by-wire technology which uses electronic controls instead of mechanical linkages.
How did electromagnetic interference contribute to the Airbus A320 crash at a European airshow?
High-energy military radars induced currents in the flight computers causing them to misinterpret pilot inputs and crash.
What is the main difference between Boeing’s Triple 7 and Airbus A320 regarding flight controls?
Boeing’s Triple 7 uses standard control sticks while Airbus A320 uses joysticks for fly-by-wire control.
Why is magnetic shielding critical in fly-by-wire flight control systems?
To prevent induced currents from magnetic fields causing erroneous control signals.
What is the ‘skin effect’ in relation to lightning strikes on aircraft?
Lightning current flows over the surface (skin) of the aircraft preventing damage to internal systems.
Why are composite materials in aircraft control surfaces a concern regarding lightning strikes?
Because composites are less conductive lightning can damage or blow apart control surfaces without a conductive path.
How do manufacturers mitigate lightning strike damage on composite aircraft parts?
By embedding a conductive layer within the composite materials to allow current dissipation.
What principle explains the generation of electricity by moving a conductor through a magnetic field?
Electromagnetic induction specifically Faraday’s law.
What did the space shuttle experiment involving a wire loop and Earth’s magnetic field demonstrate?
That moving a conductor through Earth’s magnetic field can generate significant current enough to vaporize the wire.
According to Faraday’s law how does the angle between a conductor’s motion and magnetic field lines affect induced voltage?
Maximum voltage is induced when the conductor moves perpendicular (90°) to the magnetic lines of flux; less voltage at other angles.
What does the left-hand rule help determine in electromagnetic induction?
The direction of induced current based on the directions of magnetic flux and conductor motion.
In the left-hand rule what does the thumb represent?
The direction of motion of the conductor.
In the left-hand rule what does the index finger represent?
The direction of the magnetic flux (from North to South).
In the left-hand rule what does the middle finger represent?
The direction of the induced current (from negative to positive).
What distinguishes a fixed capacitor from a variable capacitor in terms of capacitance?
A fixed capacitor has a definite unchangeable capacitance value while a variable capacitor’s capacitance can be changed by adjusting the spacing or meshing between its plates.
How is electrical isolation maintained between the plates of a variable capacitor despite the plates moving closer or further apart?
Electrical isolation is maintained by an insulator placed between the plates preventing them from touching.
What is the relationship between the area of capacitor plates and capacitance?
Larger plate area increases capacitance; smaller plate area decreases capacitance.
How does increasing the distance between capacitor plates affect voltage and capacitance?
Increasing the distance raises the voltage the capacitor can store but decreases capacitance.
What role does the dielectric material play in a capacitor’s performance?
The dielectric material affects the voltage and capacitance by its dielectric constant; higher dielectric constants increase capacitance.
How does temperature affect capacitor performance?
Temperature changes cause expansion or contraction of capacitor plates altering plate distance and thus affecting voltage and capacitance.
Why might some critical electronic components be placed in an ‘oven’ during operation?
To maintain a stable temperature ensuring consistent and reliable readings by preventing temperature-induced variations.
What is the dielectric constant and how does it vary among materials like paper mica and tantalum?
The dielectric constant measures a material’s effectiveness as an insulator; paper is about 2-3 mica 5-6 and tantalum has a high dielectric constant used in capacitors.
What happens if an electrolytic capacitor is connected backwards in a circuit?
It can explode due to its polarized nature and chemical composition.
How are paper capacitors constructed and why do they deteriorate over time?
They are made by rolling foil with wax paper as the dielectric; paper deteriorates over time losing its dielectric properties causing failure.
What distinguishes ceramic capacitors from electrolytic capacitors in terms of polarity and typical use?
Ceramic capacitors are non-polarized and used for small values (0.1 µF and smaller) while electrolytic capacitors are polarized and used for larger capacitance.
Why do capacitors in series have lower total capacitance and how does this relate to plate area and distance?
Series capacitors increase effective plate distance reducing total capacitance because capacitance decreases with increased separation.
How does connecting capacitors in parallel affect total capacitance?
Parallel connection increases total capacitance by effectively increasing the plate area allowing more charge storage.
What is resistance in an electrical circuit?
Resistance is the opposition to electron flow in a circuit.
Which symbol and unit are used to represent resistance?
Resistance is represented by the symbol R and measured in ohms (Ω).
Which material is the best conductor with the least resistance found in nature?
Silver is the best conductor with the least resistance found in nature.
How does temperature generally affect the resistance of a conductor?
Resistance increases as temperature increases (positive temperature coefficient).
Why is it problematic if an extension cord gets hot during use?
Because increased temperature raises resistance reducing current flow and causing the cord to heat more potentially leading to an electrical fire.
How does the thickness of a conductor affect its resistance?
Thicker conductors have less resistance than thinner ones.
What wire gauge is required by electrical code for 15 amp circuits in homes?
At least 14 gauge wire is required for 15 amp circuits.
What is resistivity and how is it different from resistance?
Resistivity is a material property indicating resistance to current flow while resistance is the opposition to current flow in a specific object.
What material is used as the benchmark for resistivity and assigned a value of 1.0000?
Silver is used as the benchmark for resistivity with a value of 1.0000.
What is conductance and how is it related to resistance?
Conductance is the ability of a material to pass electrons and is the reciprocal of resistance.
Why does pure water act as an insulator but tap water conducts electricity?
Pure water has very low conductivity but impurities like salts in tap water increase conductivity.
What is the purpose of a resistor in an electrical circuit?
A resistor is a component designed specifically to provide resistance in a circuit.
What are the three types of magnets you should be able to identify?
Permanent magnets temporary magnets and electromagnets.
How does the Earth function as a magnet?
The Earth acts as a giant magnet with a magnetic field generated by movements in its molten iron core.
What is the difference between permanent magnets and temporary magnets?
Permanent magnets retain their magnetic properties indefinitely while temporary magnets only exhibit magnetism when influenced by an external magnetic field.
What are flux lines in magnetism and why are they significant?
Flux lines represent the direction and strength of a magnetic field; they help visualize magnetic field patterns and interactions.
Define permeability in the context of magnetism.
Permeability is a measure of how easily a material can support the formation of a magnetic field within itself.
What is the principle of an electromagnet?
An electromagnet is created when an electric current flows through a conductor generating a magnetic field around it.
What are the three types of magnets described in basic magnetism?
Natural magnets artificial magnets and electromagnets.
How does the Earth function as a magnet?
The Earth has a giant magnetic North Pole and South Pole due to its core and crust acting like a giant magnet.
What is the difference between permanent magnets and temporary magnets?
Permanent magnets retain their magnetic properties indefinitely while temporary magnets retain only a small portion and may lose magnetism over time.
What are magnetic flux lines and what is their significance?
Magnetic flux lines are invisible lines of force surrounding a magnet showing the direction and strength of the magnetic field; they always form complete loops from north to south poles.
Define permeability in the context of magnetism.
Permeability is the ability of a material to accept magnetic lines of force.
How is a magnetic field generated by an electric current?
A magnetic field is generated whenever current flows through a wire or conductor.
What is the principle behind an electromagnet?
An electromagnet is created by current flowing through a coil of wire generating a magnetic field that is concentrated by the coil’s turns.
How can the polarity of an electromagnet be determined?
By using the left-hand rule which relates the direction of current flow to the magnetic field direction and polarity.
What is the color code used for identifying the poles of a magnet?
Red is used for the North Pole and blue is used for the South Pole.
What happens to the domains in ferromagnetic materials when magnetized?
The domains align in a common direction causing the material to become magnetized.
What is magnetic induction in the context of magnets?
Magnetic induction is the effect a magnet has on an object without physical contact.
How does adding a ferromagnetic core affect magnetic characteristics?
Adding a ferromagnetic core enhances the magnetic characteristics.
What are the three types of film resistors mentioned and how is the resistive material created in these resistors?
The three types are carbon film metal film and tin oxide film resistors. The resistive material is created by laying down a thin film of the material on a substrate during manufacturing.
Why should you avoid sneezing near an open package of surface mount resistors?
Because surface mount resistors are extremely small—almost the size of a pinhead—and a sneeze can scatter or lose them.
What is the difference between linear and logarithmic variable resistors in terms of resistance change?
Linear variable resistors change resistance proportionally to the adjustment (e.g. 50% turn equals 50% resistance) while logarithmic variable resistors change resistance following a logarithmic curve not proportionally.
Why are logarithmic variable resistors commonly used in audio applications?
Because audio signals are measured on a logarithmic scale (decibels) and are nonlinear logarithmic resistors provide a control that matches this nonlinearity resulting in a more natural volume adjustment.
What does it mean when a variable resistor is labeled as ‘audio’ on the packaging?
It means the resistor is designed for audio applications and is typically a logarithmic control to match the nonlinear characteristics of audio signals.
How does using a logarithmic variable resistor help achieve a linear perceived response in audio volume control?
Because audio signals are nonlinear a logarithmic resistor compensates for this by adjusting resistance on a curve making the perceived volume change appear linear to the listener.
What is Ohm’s Law and how does it relate current voltage and resistance?
Ohm’s Law states that current (I) equals voltage (E) divided by resistance (R) or I = E / R; equivalently voltage equals current times resistance (E = I × R) and resistance equals voltage divided by current (R = E / I).
In a series circuit how does current behave and how is total resistance calculated?
In a series circuit current is constant throughout the circuit and total resistance is the sum of the individual resistances (resistance is additive).
How does voltage behave in a parallel circuit and how is total current calculated?
In a parallel circuit voltage is constant across all branches and total current is the sum of the currents through each parallel branch.
What is Kirchhoff’s Current Law (KCL) and how does it apply to electrical circuits?
Kirchhoff’s Current Law states that the algebraic sum of all currents entering and leaving a junction (node) is zero; total current entering equals total current leaving.
How can Kirchhoff’s Current Law be used to troubleshoot electrical circuits without physical measurements?
By knowing some currents entering and leaving a node you can calculate unknown currents mathematically without opening the circuit or using a meter.
What is Kirchhoff’s Voltage Law (KVL) and what does it imply about voltage in a closed circuit?
Kirchhoff’s Voltage Law states that the algebraic sum of all voltages around a closed circuit loop equals zero meaning voltage rises equal voltage drops.
Why is it important to redraw and simplify circuits when analyzing or troubleshooting?
Redrawing simplifies complex circuits into equivalent circuits making it easier to analyze and understand circuit behavior and identify faults.
What are the five basic parts of an electrical circuit that must be checked for functionality?
The five basic parts are the voltage source load conductor (wiring) controlling device and protective device.
What is a resettable fuse and how does it function in consumer electronics?
A resettable fuse is a protective device that trips during a fault and can reset itself after being unplugged and allowed to cool restoring circuit function without replacement.
Why is it recommended to unplug electronic devices overnight to fix certain issues?
Unplugging allows resettable fuses and capacitors to fully discharge and reset restoring the device to its factory state and resolving glitches.
What is the primary function of the P3 Orion aircraft in military operations?
It is a submarine hunter equipped with magnetic anomaly detection (MAD) gear.
How does the radar operator typically detect a submarine using radar scans?
By performing a circular scan to detect blips then switching to a sector scan to pinpoint the target before shutting off the radar.
What happens after the radar operator identifies a submarine contact and uses the autopilot?
The autopilot brings the aircraft to the target point where the operator uses MAD gear to detect magnetic anomalies and may deploy a flare and torpedo.
Why is it important to periodically remove the magnetic field from a submarine’s hull?
Because the hull’s magnetic signature builds up over time and can be detected by magnetic anomaly detection systems.
What is ‘retentivity’ in the context of submarine hulls?
The ability of a material to retain its magnetic field after the magnetizing force is removed.
Why are magnetic shields made of low reluctance materials used in electronics?
To protect electronic equipment from magnetic flux lines that could cause interference or damage.
How does Earth’s magnetic field influence the visibility of the Aurora Borealis?
Earth’s magnetic field attracts charged solar particles to the poles ionizing the atmosphere and creating the Aurora Borealis.
What is the significance of the British radar technology mentioned in the context of submarine detection?
It could detect very small objects like a beer can floating 400 miles away greatly enhancing detection capabilities.
Why do submarine operators shut down radar quickly after detecting a contact?
To avoid revealing their position to the enemy by minimizing radar emissions.
What role does the magnetic anomaly detection (MAD) gear play in anti-submarine warfare?
It detects magnetic anomalies caused by submarines confirming their presence underwater.
What is the key characteristic of current in a series circuit?
Current is constant throughout a series circuit.
How is total resistance calculated in a series circuit with multiple resistors?
Total resistance is the sum of all individual resistors’ resistances.
Why is a series circuit also called a voltage divider?
Because the total voltage is divided proportionally across each resistor based on its resistance.
In a parallel circuit what electrical quantity remains constant across all branches?
Voltage remains constant across all branches in a parallel circuit.
What is a parallel circuit commonly known as and why?
A current divider because the total current splits among the parallel branches.
How do you calculate the equivalent resistance between two nodes in a parallel network?
Equivalent resistance equals the product over the sum of the two resistors (R_eq = (R2 * R3) / (R2 + R3)).
What defines a closed circuit and is it always good?
A closed circuit is one where current can flow; it can be good or bad depending on the desired outcome.
What causes a switch in a pressure washer to fail by remaining permanently closed?
The switch contacts get welded together due to excessive heat from improper wiring or high resistance.
What is an open circuit and how does it differ from a short circuit?
An open circuit is a break preventing current flow; a short circuit is an unintended low-resistance path causing excessive current.
How does increasing voltage affect current in a circuit if resistance is constant?
Increasing voltage increases current proportionally.
How does increasing resistance affect current in a circuit if voltage is constant?
Increasing resistance decreases current inversely.
State Ohm’s Law and its formula.
Ohm’s Law states voltage equals current times resistance V = I × R.
Using the Ohm’s Law triangle how do you calculate current if voltage and resistance are known?
Current equals voltage divided by resistance I = V / R.
What is inductance and what symbol represents it in electrical circuits?
Inductance is the property of an electrical conductor that opposes a change in current flow represented by the capital letter L.
How does an inductor store energy and what type of field is involved?
An inductor stores energy in a magnetic field which is an electromagnetic field.
According to Lenz’s law what direction does the induced EMF take relative to the change that produced it?
The induced EMF is always in a direction to oppose the effect that produced it.
What happens to the magnetic field and induced EMF when current through an inductor is suddenly turned off?
The magnetic field collapses and produces a counter EMF in the opposite direction to the original current flow.
How does the frequency of AC affect the inductive effect in an inductor?
Higher AC frequency increases the rate of change of current making the inductive effect more pronounced.
What is the unit of inductance and how is one Henry defined?
The unit of inductance is the Henry (H) defined as the inductance required to induce an EMF of one volt when the current changes at one ampere per second.
How does the number of turns in an inductor coil affect its inductance?
Doubling the number of turns approximately doubles the inductance.
What effect does using a magnetic core versus a non-magnetic core have on an inductor’s inductance?
A magnetic core increases the inductance compared to a non-magnetic core.
Why should non-magnetic tools be used to adjust variable inductors?
Because magnetic tools can alter the magnetic field and affect the inductance leading to inaccurate adjustments.
What is an air core inductor and what is its typical inductance range?
An air core inductor has no magnetic core material and is used for inductances up to about 5 millihenries.
What is the significance of a toroidal core in inductors?
A toroidal core contains the magnetic field within the core providing high inductance in a small size and reducing stray magnetic fields.
How are inductors combined in series and parallel circuits to find total inductance?
In series inductances add directly; in parallel the total inductance is found using the reciprocal formula similar to resistors.
What is the LR time constant formula for an RL circuit and what does it represent?
The time constant T equals inductance L divided by resistance R (T = L/R) representing the time for current to reach about 63.2% of its final value.
How many time constants are generally required for current in an RL circuit to be considered fully established or decayed?
Five time constants are required to effectively reach 100% or zero current.
What is the key property of inductance that allows inductors to stabilize current flow in circuits?
Inductance opposes changes in current helping to stabilize current flow by resisting sudden increases or decreases.
What is the primary application of inductors in electronic circuits as mentioned?
Inductors are primarily used for filtration especially in AC circuits to filter specific frequencies.
How can a transformer be used as an inductor?
By using only one coil (primary) and not connecting the secondary a transformer can function as an inductor.
What is the easiest method to identify a resistor’s value?
When the resistor has its value printed directly on it using numbers and letters.
How does the alphanumeric code on a resistor help in identification?
It provides detailed information about the resistor’s style temperature characteristics resistance value and tolerance which must be decoded using charts or tables.
In the alphanumeric code ‘5112’ on a resistor what does the ‘2’ represent?
The number of zeros to add at the end of the preceding digits.
How should you orient a resistor to read its color code correctly?
Hold the resistor so that the band closest to the edge is on the left then read the color bands from left to right like a book.
What resistance value does the color code orange white red gold represent?
3 900 ohms or 3.9 K ohms with a 5% tolerance.
Why is memorizing the resistor color code important despite not being heavily tested in quizzes?
Because it is essential for practical electronics work and commonly asked in job interviews.
What does the letter ‘F’ typically represent in resistor tolerance codes?
It indicates the tolerance percentage which must be looked up as it varies (e.g. 5% 2% 10% 20%).
What is the significance of the resistor style code like ‘rn60’ in an alphanumeric resistor code?
It identifies the resistor’s construction type such as carbon composition wire wound or film.
What happens to flux lines when they are looped together in a coil?
The flux lines are brought together and concentrated at the center of the loop establishing a North and South Pole.
What two poles are established when a magnetic field is created?
A North Pole and a South Pole are established.
What are three ways to increase the strength of a magnetic field in a coil?
Increase the number of wire turns increase the current and increase the number of flux lines generated.
What is the recommended initial step before reading a textbook chapter in this electronics course?
Read through the course objectives in the syllabus first.
After reading a chapter what should students do to reinforce their understanding according to the instructor?
Go through the chapter carefully solve every example and practice problem with a calculator and then read through the chapter again quickly.
How should students handle content in the textbook that they already know?
They should not spend excessive time on it and instead focus their energy on areas they do not understand.
When does the instructor prefer to conduct lectures on a chapter?
Only after students have read the chapter completed their homework and done peer reviews in teams.
What resources related to the lectures are made available to students online?
Slides audio files in MP3 format and eventually video recordings of the lectures.
Why does the instructor provide recordings and slides openly to students?
Because he wants to give as much information as possible and has nothing to hide.
What analogy does the instructor use to explain why students might want to review lectures multiple times?
Watching a favorite movie multiple times to catch details missed the first time.
What is the instructor’s attitude towards students taking notes during lectures?
Students should hone their note-taking skills and pay attention to emphasized points as they may appear on quizzes exams or in industry.
How does the instructor measure student success beyond passing exams?
By where students are in their careers 5 or 10 years later and how the course helped them in their professional lives.
What example does the instructor give to illustrate the lasting impact of the course on students?
A former student from 1993 contacted him years later to reconnect and discuss how the course influenced his career.
What does DC stand for in electronics?
DC stands for direct current.
What is the main focus of the first section of the book on electronics?
The first section deals with DC circuits and the fundamentals of electricity.
Why are the first few chapters of the electronics book described as ‘sacred’ or critical?
Because they cover fundamental concepts essential for success in electricity and electronics.
What are the four fundamental properties that drive the entire electrical and electronics industry?
Voltage current resistance and power.
Why is it important to fully understand voltage current resistance and power in electronics?
Because knowing these properties means understanding what is happening inside an electrical circuit.
How does the curriculum for the electronics program stay relevant and competitive?
It is derived from input by a local industry advisory committee that regularly meets to provide guidance.
What is the definition of matter as described in the content?
Matter is anything that occupies space and has weight.
Where can a large abundance of absence of matter be found according to the content?
In space which is essentially empty space with no matter.
What is an element according to the content and how many are known to exist?
An element is the basic building block of all matter that cannot be reduced to a simpler substance by chemical means; about 100 known elements exist.
What unit is used to measure current and what symbol represents current flow in a circuit?
The unit is the ampere (amp) and the symbol used to represent current flow is ‘I’.
What is the difference between conductors insulators and semiconductors?
Conductors allow current to flow easily insulators resist current flow and semiconductors have properties between conductors and insulators.
What is the difference of potential electromotive force and voltage?
They all refer to the potential difference that causes current to flow in a circuit; voltage is the term commonly used.
Why is resistance important in an electrical circuit and how is it measured?
Resistance opposes current flow in a circuit; it is measured in ohms and represented by the symbol ‘R’.
What property of a wire affects the current passing through it?
Resistance.
What happens to a wire if the current passing through it is increased beyond a certain limit?
The wire heats up and can eventually break or act like a fuse.
Why is using capacitors with a 20% tolerance problematic in certain circuits?
Because the circuit requires capacitors within a tighter tolerance range to function correctly and 20% tolerance capacitors cause the circuit to fall outside the acceptable zone.
What method was used to improve capacitor selection for circuits requiring tighter tolerance?
Testing a bin of 20% tolerance capacitors individually and sorting out those that actually had a tighter tolerance around 5% to use in the circuit.
What was the suggested company-wide improvement to reduce rework caused by capacitor tolerance issues?
To purchase capacitors with a 5% tolerance instead of 20% tolerance capacitors.
What was the reason given for the company continuing to use 20% tolerance capacitors despite the problems?
The production manager had a personal connection to a supplier of cheap capacitors and was buying them in bulk ignoring the technical requirements.
What is the defining characteristic of a series circuit regarding current flow?
In a series circuit the current is constant through all components because there is only one path for current flow.
How is total resistance calculated in a series circuit?
Total resistance in a series circuit is the sum of the individual resistances of all components.
What must the sum of voltage drops across components in a series circuit equal?
The sum of the voltage drops across all components must equal the total voltage supplied to the circuit.
Why is a series circuit also known as a voltage divider?
Because the voltage supplied is divided among the series components proportionally to their resistance creating voltage drops that add up to the total voltage.
What is the relationship between voltage drop and resistance size in a series circuit?
Voltage drop across a resistor in series is proportional to its resistance; larger resistance causes a larger voltage drop.
What is the most important thing to remember about current in a series circuit?
Current is constant throughout a series circuit because there is only one path for current flow.
What is the defining characteristic of voltage in a parallel circuit?
Voltage is constant across all components connected in parallel.
How does current behave in a parallel circuit with multiple branches?
The total current divides among the parallel branches with current inversely proportional to each branch’s resistance.
What formula is used to calculate total resistance for two resistors in parallel?
The product over sum formula: (R1 × R2) / (R1 + R2).
What is the thumb rule for the total resistance of equal-value resistors in parallel?
Total resistance equals the resistance of one resistor divided by the number of resistors in parallel.
What is the thumb rule regarding the bleeder current in a loaded voltage divider circuit?
The bleeder current should be one-tenth (1/10) of the total load current for circuit stability.
How do you calculate the current required by a device using power and voltage?
Current (I) equals power (P) divided by voltage (V) I = P / V.
Why is it important to consider efficiency when calculating current from power and voltage?
Because devices are not 100% efficient; some power is lost as heat so actual current may be higher than calculated.
What happens to the voltage drop across a resistor if the resistance value increases in a series circuit?
The voltage drop across that resistor increases proportionally with its resistance.
How do you find the total current in a series circuit once total resistance and voltage are known?
Use Ohm’s law: total current I = total voltage V divided by total resistance R I = V / R.
What is the relationship between total power and individual power consumptions in series and parallel circuits?
Total power is the sum of the power consumed by each individual component in the circuit.
How can you identify a series circuit by its connections?
A series circuit has only one way in and one way out meaning components are connected end-to-end with a single path for current.
What is the key difference between a voltage divider and a current divider?
A voltage divider (series circuit) divides voltage among components while a current divider (parallel circuit) divides current among branches.
Why is it important to connect loads in parallel to a voltage divider when powering devices?
Because connecting loads in parallel ensures each load receives the correct voltage from the voltage divider without altering the voltage division significantly.
What is the formula for capacitance and how does changing the plate area or distance affect it?
Capacitance (C) equals charge (Q) divided by voltage (V) C = Q/V. Increasing the plate area increases capacitance while increasing the distance between plates decreases capacitance.
What does the RC time constant represent in a capacitor charging circuit?
The RC time constant represents the time required for a capacitor to charge up to 63.2% of the applied voltage or discharge down to 36.8%.
In a series RC circuit how long does it take for a capacitor to fully charge to nearly 100% of the applied voltage?
It takes approximately five time constants (5 × R × C) for the capacitor to charge close to 100%.
What voltage appears across the resistor in a series RC circuit when the capacitor is fully charged after five time constants?
The voltage across the resistor is zero volts when the capacitor is fully charged.
How does voltage divide between the resistor and capacitor during charging in a series RC circuit?
As the capacitor voltage increases the resistor voltage decreases proportionally acting as a voltage divider.
Why is five time constants commonly used to describe capacitor charging time instead of six?
Because after five time constants the capacitor is about 99.3% charged which is close enough to 100% for most practical and exam purposes.
What factors affect capacitance in a capacitor?
Capacitance is affected by the area of the plates distance between the plates types of materials used and temperature.
What are the common types of capacitors and their symbols?
Common capacitor types include electrolytic paper plastic ceramic and variable capacitors. The fixed capacitor symbol is a pair of parallel lines and the variable capacitor symbol includes an arrow through the plates.
How do you add capacitances in series and parallel configurations?
In series capacitances add like resistors in parallel (using the reciprocal formula). In parallel capacitances add directly (sum of capacitances).
What is the formula to calculate the capacitive time constant in an RC circuit?
The capacitive time constant T is calculated as T = R × C where R is resistance and C is capacitance.
What are the six most common voltage sources you should be able to identify?
The six most common voltage sources are not explicitly listed in the extract.
How do you define a cell and a battery in basic electronics?
A cell is a single electrochemical unit that produces electricity while a battery is a combination of two or more cells connected together.
What is the difference between primary and secondary cells?
Primary cells are single-use and cannot be recharged while secondary cells are rechargeable and can be used multiple times.
How are cells and batteries rated in electronics?
Cells and batteries are rated based on their voltage and current output capabilities.
What are the ways to connect cells or batteries to increase current voltage or both?
Cells or batteries can be connected in series to increase voltage in parallel to increase current or a combination of both to increase voltage and current.
What is voltage rise and voltage drop in electrical circuits?
Voltage rise is an increase in electrical potential energy in a circuit while voltage drop is a decrease in electrical potential energy across a component.
What are the two types of grounds associated with electrical circuits?
The two types of grounds are earth ground and chassis ground.
What are the three essential components that every electric circuit must have?
A voltage source a load and a conductor.
How does a load function in an electric circuit?
It converts electrical energy into another form of energy such as light heat or motion.
What is the role of a controlling device in an electric circuit?
To control the flow of current within the circuit.
What purpose do protective devices serve in an electric circuit?
They protect the circuit by interrupting current flow in case of faults examples include fuses and circuit breakers.
According to the extract what is the best approach when troubleshooting complex electronic systems?
Go back to basics by verifying voltage sources loads conductors controlling devices and protective devices.
Why is it important to verify the voltage source first when diagnosing an electrical problem?
Because the voltage source provides the energy needed for the circuit to function; if it’s faulty the circuit won’t work.
What is an example of a complex controlling device mentioned in the extract?
A microprocessor with 1.9 billion transistors.
How did the author identify the cause of failure in the Direct TV DVR?
By finding a disguised fuse covered with heat shrink that was blown and replacing it.
What lesson does the author emphasize about problems in sophisticated electronic equipment?
That problems are usually simple and can be solved by following basic troubleshooting protocols.
What is meant by ‘graceful degradation’ in electronic systems?
A design where parts of the system can fail but the whole system continues to operate.
What principle does an AC generator use to convert mechanical energy into electrical energy?
Electromagnetic induction.
In an AC generator what types of magnets can be used to create the magnetic field?
Permanent magnets or electromagnets.
Why do car alternators use electromagnets (field windings) instead of permanent magnets?
Because field windings produce an electromagnetic field powered by the battery allowing control of the magnetic field strength.
According to Faraday’s law how much current is generated when the armature winding is parallel to the magnetic flux lines in an AC generator?
Zero current is generated.
What happens to the current generated in an AC generator when the armature winding is perpendicular to the magnetic flux lines?
Maximum current is generated.
Describe the waveform produced by an AC generator during one full rotation of the armature.
A sinusoidal waveform with half positive and half negative cycles.
Who is credited as the father of the AC generator and advocate for AC power?
Nikola Tesla.
What is the main difference between the contact mechanisms of AC and DC generators?
AC generators use slip rings maintaining contact for 360° DC generators use a commutator maintaining contact for 180°.
What is a relay and how does it function in electrical circuits?
A relay is an electromechanical switch that uses an electromagnetic coil to open or close contacts.
What is the difference between a relay and a solenoid in terms of mechanical movement?
A relay has a moving armature that operates contacts; a solenoid has a moving plunger that performs mechanical work.
How does a phonograph pickup use electromagnetic principles to reproduce sound?
A permanent magnet attached to a stylus produces a magnetic field that varies as the stylus tracks the record groove inducing a voltage that replicates the audio signal.
Why do magnetic recordings degrade over time and with repeated playback?
Because the magnetic particles lose their magnetization due to Earth’s magnetic field and electromagnetic interference and playback slightly erases the recorded pattern each time.
What principle does a DC motor operate on?
A current-carrying conductor placed at right angles to a magnetic field experiences a force causing motion at right angles to both current and field.
How do the generators at the Grand Coulee Dam use motor-generator sets to manage energy storage and generation?
They pump water to a higher elevation during low demand using motors and generate electricity by letting water flow back during peak demand using generators.
What role do deflection windings play in a cathode ray tube (CRT) monitor?
They control the horizontal and vertical movement of the electron beam to paint the image on the screen.
What is the relationship between unlike and like magnetic poles?
Unlike poles attract; like poles repel.
What is the function of slip rings in an AC generator?
They maintain electrical contact with the rotating armature for the full 360° rotation allowing continuous AC output.
Why are relays still used despite being electromechanical and prone to failure?
Because they can handle high current loads and provide job security for technicians due to their need for maintenance and troubleshooting.
How does a magnetic recording store information on tape?
By magnetizing iron oxide particles on the tape in a pattern corresponding to the audio or data signal using a fluctuating magnetic field from the record head.
What are the three fundamental types of resistor circuit configurations in electronics?
Series circuit parallel circuit and compound (combination) circuit.
How do you calculate the total resistance in a series circuit?
By adding the resistance values of all resistors: RT = R1 + R2 + R3 + …
Why might the measured resistance in a real circuit differ from the theoretical total resistance?
Due to factors like resistor tolerance corrosion and bad solder joints adding extra resistance.
What is the formula to calculate total resistance in a parallel circuit with multiple resistors?
1/RT = 1/R1 + 1/R2 + 1/R3 + … (reciprocal of total resistance equals sum of reciprocals of individual resistances).
Why does adding resistors in parallel reduce the total resistance of the circuit?
Because adding parallel paths increases total conductivity lowering overall resistance.
What is the thumb rule regarding total resistance in a parallel circuit compared to the smallest resistor?
Total resistance will always be less than the smallest individual resistor in the parallel network.
How can you quickly estimate total resistance in a parallel circuit if all resistors have equal resistance?
Divide the resistance value by the number of resistors: RT = R / n.
What is the ‘product over sum’ formula and when is it used?
RT = (R1 × R2) / (R1 + R2); used only for two resistors in parallel.
How do you calculate the total resistance of a compound circuit with two resistors in parallel and others in series?
Calculate the parallel resistance first using product over sum then add series resistors: RT = R1 + (R2 × R3)/(R2 + R3) + R4.
What is a node in the context of resistor circuits?
A point where two or more wires are joined together.
What is magnetic wire and why is it used for making coils?
Magnetic wire is thin copper wire coated with a thin lacquer that acts as an electrical insulator preventing short circuits when the wire is wound into coils.
Why is the lacquer coating on magnetic wire important?
The lacquer coating acts as an electrical insulator to prevent the wire from shorting when wound over itself in coils.
What happens if too much current passes through a coil made with magnetic wire?
Excessive current causes the coil to heat up which can damage the lacquer coating and ultimately ruin the coil.
What is the smallest particle of an element that retains its identity?
An atom.
Where is the nucleus located in an atom?
At the center of the atom.
What charge does a proton carry and where is it found?
A proton carries a positive charge and is located in the nucleus.
What is the charge of a neutron and where is it located?
A neutron is neutrally charged (no charge) and is located in the nucleus.
What charge does an electron have and where does it orbit?
An electron has a negative charge and orbits the nucleus.
Why do matter in its neutral natural state have no net charge?
Because it has an equal number of protons (positive charge) and electrons (negative charge) that cancel each other out.
What is the atomic number of an element?
The number of protons in the nucleus of the atom.
How is atomic weight determined?
By counting the total number of protons and neutrons in the nucleus.
What are electron shells and how are they filled?
Electron shells are orbital paths around the nucleus where electrons orbit and they are filled in sequence from the innermost shell outward.
What is the valence shell and why is it important?
The valence shell is the outermost electron shell of an atom important because it determines the atom’s chemical properties and behavior.
What is the naming scheme for electron shells starting from the innermost?
K L M N O Q shells with K being the innermost shell.
Why do electronics professionals only work with valence electrons?
Because manipulating electrons in the valence shell affects electrical behavior without altering the nucleus which can be dangerous.
What defines a good electrical conductor in terms of valence electrons?
Materials with three or fewer electrons in their valence shell are typically good conductors.
Which element has the best electrical conductivity found in nature?
Silver.
Why are gold-plated connectors used in electronics despite gold not being the best conductor?
Because gold resists oxidation and corrosion better than silver or copper ensuring reliable long-term connections.
What is the best natural electrical insulator found on Earth?
Mica.
What are insulators in electronics?
Materials that prevent the flow of electricity by stabilizing or absorbing valence electrons.
Why is oil used in some electrical transformers and cooling systems?
Because oil is an insulator that also helps draw heat away from circuits improving performance and preventing overheating.
What safety advice is given regarding experimentation with atomic nuclei?
Avoid experimenting with the nucleus of atoms because it can cause dangerous effects; only work with electrons especially valence electrons.
What are the six methods of producing electricity mentioned in the content?
Friction magnetism chemicals light heat and pressure.
How does friction produce electricity and what is a common natural example of this?
Friction produces electricity by the movement of electrons caused by rubbing or atmospheric friction; a common natural example is lightning during storms.
What is the primary difference between direct current (DC) and alternating current (AC) as described?
DC is the flow of electrons in only one direction (negative to positive) while AC is current that reverses direction back and forth.
What is a chemical cell and how is it related to batteries?
A chemical cell is a device that produces electrical energy through chemical reactions; multiple cells connected together form a battery.
What is the voltage output of a typical cell such as AAA AA C or D size?
1.5 volts DC.
How does connecting cells in series affect voltage and current?
Connecting cells in series increases the total voltage while the current remains the same.
How does connecting batteries in parallel affect voltage and current capacity?
Voltage remains the same but the current capacity (amp hours) increases allowing longer usage time.
What is the difference between primary and secondary cells?
Primary cells cannot be recharged and are for one-time use; secondary cells can be recharged and used multiple times.
What is the role of specific gravity in lead acid batteries?
Specific gravity measures the density of the electrolyte fluid indicating the battery’s charge level; higher specific gravity means more stored electrons.
What is voltage rise and voltage drop in an electrical circuit?
Voltage rise is the energy supplied to the circuit (e.g. by batteries) and voltage drop is the energy consumed by the load; they should be equal.
What are the two types of grounds associated with electrical circuits?
Earth ground (a rod driven into the Earth at zero potential) and electrical ground (chassis ground used as a common reference point).
Why is the chassis of a car used as electrical ground?
Using the chassis as ground saves wiring by providing a common conductive path for electrical return currents.
What is a thermocouple and how does it produce voltage?
A thermocouple is made of two dissimilar metals welded together; when heated at the junction it produces a voltage proportional to the temperature.
What is the piezoelectric effect and where is it commonly used?
The piezoelectric effect produces a small voltage when pressure is applied to certain crystals; used in microphones phonograph pickups and pressure sensors.
Why are lithium primary cells preferred for certain applications?
They have a longer shelf life higher voltage output and perform well across a wide temperature range including extreme cold and heat.
What is the significance of the 9-volt battery’s voltage and construction?
A 9-volt battery is made of multiple 1.5-volt cells connected together to provide a total of 9 volts; it was commonly used in transistor radios.
What is the memory effect in nickel-cadmium (NiCad) batteries?
If not fully discharged before recharging NiCad batteries ‘remember’ a reduced capacity range limiting their usable charge cycle.
How should NiCad batteries be properly charged to avoid damage?
They should be charged with a timed trickle charge gradually reaching full charge without overheating or quick shutoffs.
Why is grounding important in electronic systems and what problems can arise without proper grounding?
Proper grounding prevents differences in potential that can cause sparks fires or erratic behavior in electronic devices.
What are the three basic parts of an electronic circuit?
The three basic parts of an electronic circuit are the power source the load and the control element.
Name three types of circuit configurations.
The three types of circuit configurations are series parallel and series-parallel circuits.
How can current flow be varied in a circuit?
Current flow can be varied by changing the resistance or voltage in the circuit.
State Ohm’s law with reference to current voltage and resistance.
Ohm’s law states that current (I) equals voltage (V) divided by resistance (R) or I = V / R.
How can you solve problems using Ohm’s law for current resistance and voltage?
By rearranging Ohm’s law formula: I = V / R V = I × R and R = V / I you can calculate any one of the three variables if the other two are known.
What is the definition of electric power in an electric circuit?
Electric power is the instantaneous rate at which work is done in an electric circuit calculated as voltage multiplied by current.
How does voltage relate to current and work in an electric circuit?
Voltage creates current by causing electrons to move and when voltage and current are present work is being done in the circuit.
What is the basic unit of electric power and how is it calculated?
The basic unit of electric power is the watt calculated as power (P) equals voltage (V) times current (I) or P = V × I.
Why is the power company more accurately described as a ‘voltage company’?
Because the power company provides the voltage (electrical pressure) to your home but you provide the current path by turning on devices that consume power.
How is power consumption measured and charged by electric companies?
Power consumption is measured in kilowatt-hours (kWh) which represents consuming 1 000 watts over one hour and customers are charged based on this unit.
Explain why wattage is greater when the same amount of work is done in a shorter period of time.
Because power is the rate of doing work completing the same work faster requires more power resulting in higher wattage.
What is the significance of power being additive in series and parallel circuits?
The total power dissipated in a series or parallel circuit equals the sum of the power dissipated by each individual component.
How can you calculate the power dissipated by an individual component in a circuit?
By multiplying the voltage drop across the component by the current flowing through it (P = V × I).
Why do resistors generate heat when current flows through them?
Because resistance opposes electron flow causing electrical energy to be converted into heat as a byproduct.
What happens if a resistor is subjected to power beyond its rated capability?
The resistor will overheat and fail potentially causing damage to the circuit.
What are phantom loads in a home electrical system?
Phantom loads are small amounts of power consumed by devices that are plugged in but turned off or in standby mode.
How can thermal imaging be used in electrical systems?
Thermal imaging detects heat generated by electrical components or connections identifying issues like excessive resistance or failing parts.
What is the relationship between power voltage and current known as?
It is known as Watt’s law which states power equals voltage multiplied by current (P = V × I).
Why is power consumption in microelectronics typically less than one watt?
Because microelectronics operate at very low voltages and currents resulting in power consumption measured in milliwatts or microwatts.
How does increasing power affect the work done in electronic or mechanical systems?
Increasing power allows more work to be done in a shorter time or greater work overall such as accelerating a car faster or launching a space shuttle.
What is the practical importance of calculating power in commercial broadcasting?
It ensures compliance with FCC regulations by verifying that transmitters do not exceed authorized power limits preventing interference.
How does power dissipation relate to the thermal profile of electronic equipment?
Power dissipation generates heat affecting the temperature of equipment; monitoring thermal profiles helps detect inefficiencies or failures.
Why is it important to use the voltage drop across a component rather than total voltage to calculate power consumption?
Because power consumption depends on the voltage specifically across the component and the current through it not the total circuit voltage.
What defines a conductor in terms of valence electrons?
A conductor has three or fewer electrons in its valence shell.
How many valence electrons do insulators have and why does this make them insulators?
Insulators have five or more valence electrons which restricts free electron movement making them poor conductors.
What is a semiconductor and how many valence electrons does it have?
A semiconductor has four valence electrons and can function as either a conductor or an insulator depending on conditions.
Name three elements commonly associated with semiconductor materials.
Germanium carbon and silicon.
What causes voltage in an electrical system?
Voltage is caused by the presence of positive and negative ions created through ionization which is the gain or loss of electrons.
Explain the process of ionization in the context of electricity generation.
Ionization is the process of gaining or losing electrons creating charged ions that generate voltage and enable current flow.
Define current in terms of electron movement.
Current is the movement of electrons from negatively charged atoms to positively charged atoms.
What is a coulomb and how many electrons does it represent?
A coulomb is a unit of electrical charge representing 6.24 × 10^18 electrons.
How is the ampere defined in terms of coulombs and time?
One ampere is the current when one coulomb of charge passes a point in one second.
What is the relationship formula between current (I) charge (Q) and time (T)?
I = Q / T where I is current in amperes Q is charge in coulombs and T is time in seconds.
What are the two fundamental laws of electrostatic charges?
First law: Like charges repel each other. Second law: Opposite charges attract each other.
What is a superconductor and under what conditions does it exist?
A superconductor is a material with zero electrical resistance existing only at very low temperatures in laboratory conditions.
How does rubbing a neutral object like a calculator create a positive ion?
Rubbing removes electrons from the object leaving more protons than electrons thus creating a positive ion.
What happens to the cloth when electrons are transferred from the calculator to it by rubbing?
The cloth becomes negatively charged because it gains extra electrons.
Why is it important that electrons follow a correct path in a circuit?
To perform useful work and avoid short circuits which occur when electrons complete the path improperly.
What is the significance of holes in semiconductor physics?
Holes represent the absence of electrons and appear to move in the opposite direction to electron flow important for understanding semiconductor devices.
How fast does current flow through a conductor?
Current flows at nearly the speed of light approximately 186 000 miles per second or 300 million meters per second.
What is the unit of resistance and who is it named after?
Resistance is measured in ohms named after George Simon Ohm and represented by the Greek letter Omega (Ω).
What is the difference between electron flow and conventional current flow?
Electron flow is from negative to positive while conventional current flow is considered from positive to negative (hole flow).
What are the common metric prefixes used in electronics for large and small quantities?
Large: kilo (10^3) mega (10^6) giga (10^9) tera (10^12). Small: milli (10^-3) micro (10^-6) nano (10^-9) pico (10^-12).
What are the two main classifications of resistors based on their resistance value?
Fixed value resistors and variable value resistors.
What does the tolerance of a resistor indicate?
The amount the resistor’s resistance may vary and still be acceptable.
How does the tolerance percentage affect the cost of manufacturing resistors?
Larger tolerance typically makes the resistor cheaper to manufacture.
What is an example of a high tolerance value for resistors and why is it considered unusual?
Plus or minus 20% tolerance; it’s unusual because such a large variation is rarely acceptable in precise applications.
If you have a 100 ohm resistor with a tolerance of ±20% what is the possible range of its actual resistance?
Between 80 ohms and 120 ohms.
Why might working with components that have ±20% tolerance be frustrating in industry?
Because it challenges the expectation of accuracy and precision in practical applications.
What is a molded carbon resistor and why is it commonly used?
A resistor made of molded carbon; it is commonly used because it is inexpensive and available in standard resistor values.
Why do resistors come in standard sizes rather than arbitrary values like 103.5 ohms?
Because standard sizes ensure compatibility and availability similar to standard tire sizes for wheels.
What is a wire wound resistor and in what type of circuits is it typically used?
A resistor made by winding wire to create resistance; used in high current circuits.
Can the resistance value of a resistor change over time and what might cause this?
Yes it can change slightly due to heating and changes in composition.
Do tolerances of multiple resistors add up when used together in a circuit?
Yes tolerances can have a cumulative effect.
What problem can arise when all components in a circuit are within tolerance individually but the circuit still fails?
The cumulative effect of tolerances pulling in different directions can cause the integrated system to malfunction.
Why does smelling a transformer or motor indicate it will no longer work properly?
Because the smell indicates it has overheated and its integrity is compromised so it will never work right again.
How can the magnetic field of a coil be increased using a core?
By inserting a ferromagnetic core usually iron into the center of the coil and wrapping the coil around it.
Why was residual magnetism a significant problem for submarines made of ferromagnetic materials?
Because the submarine would gradually become magnetized by the Earth’s magnetic field making it detectable by magnetic anomaly detection equipment.
How does magnetic anomaly detection help in anti-submarine warfare?
It detects magnetic variations caused by large submerged ferromagnetic objects like submarines revealing their presence even if they are quiet and not visible.
