H - Electronics Flashcards
one coloumb is the combined charge of how many electrons
6.241 x 10 to the power of 18
Name examples of insulators
rubber
plastic
ceramics
air
dry paper
pure water
wood
what is the SI unit of voltage and what is it measured in
voltage (V) is measured in Volts (V)
what are capacitors
the terminal electronic component that stores electrical energy in an electric field
what is the difference between conventional and actual current flow
electrons flow from negative to positive points in a circuit in actuality, due to their negative charge, but this is the other way round in conventional current flow.
Define ‘joule’
DEF:
the SI unit of work or energy, equal to the work done by a force of one newton when it’s point of application moves one meter in the direction of action of the force, equivalent to one 3600th of a watt-hour
what happens when a capacitor is connected to an AC supply, with a low frequency
the capacitor will have enough time to charge in one direction, and the opposition to current flow will be high
what is the SI unit of resistance and what is it measured in
resistance (R) is measured in ohms (Ω)
name examples of semi-conductors
carbon
silicon
germanium
what happens to the low frequencies across the capacitor in an LCR circuit
the low frequencies drop across it, and create a low pass filter
what is the SI unit of time constant
τ (tau)
what does a transducer do
converts one type of energy into another one
what is the difference between balanced and unbalanced audio
unbalanced cables carry a ground wire, balanced cables carry 2 copies of the same signal which are reversed and phase flipped.
what is the SI unit of power and what is it measured in
power (P) is measured in Watts (W)
what is impedance matching
when source output (source) equals source input (load), and maximum power is transferred.
what is an LR circuit
an inductor and a resistor in circuit series
how much is the cutoff frequency attenuated by in dB
3 dB
what is the rule of thumb for impedance briding
low output (source) should meet high input (load) impedances
Define power.
What is the unit of measurement used?
DEF: the rate of work done over time or the rate of using energy.
measured in watts (W)
the more a capacitor is charged, the higher the….
opposition to current flow
define ohms law
current is directly proportional to voltage and indirectly proportional to resistance
what is the output across the resistor in a CR circuit
a high pass filter
what are inductors, and what does inductance do
An inductor is simply a coil of wire. When current passes through the coil, an electrical field is generated. The field has been “induced.” The bigger the coil or the greater the number of turns, the greater the induced field. This phenomenon is called “inductance.”
How many joules are in 1 Watt?
1 W = 1 joule per second
What determines the amount of charge that can be held by a capacitor?
size of plates, distance between them and the material used for the dielectric
what happens to the mid frequencies across the resistor in an LCR circuit
the mid frequencies will drop across it, and create a band pass filter
what is current
the rate of flow of electrons, and describes the number of electrons that pass a point per second
what is reactance
it is the opposition to a circuit element to a change in current or voltage, due to that elements inductance or capacitance. It is a frequency dependent opposition
what is the output across the inductor in a LR circuit
a high pass filter
what do transformers do
they bring the voltage up or down, and they only work with AC
what is a capacitors time constant
the time constant determines the time it takes the capacitor to charge
What does the frequency of AC reflect?
how many times in a second the current changes direction
How does a capacitor store charge?
when connected to an electric circuit one plate attracts electrons and one repels them, leading to a buildup of positive charge on one plate and an equal negative charge on the other.
What kind of electricity is used by most of our devices?
DC
how would you describe electricity
a form of energy resulting from the existence of particles either statically as an accumulation of charge or dynamically as a current.
what is the SI unit of capacitance and what is it measured in
capacitance (C) is measured in Farads (F)
What is a semi-conductor?
a substance that allows current to flow only under specific conditions
can have very useful properies like…
allowing current to flow more easily in one direction than the other
showing variable resistance, sensitivity to light or heat
what is the SI unit of impedance and what is it measured in
impedance (Z) is measured in ohms (Ω)
what factors effect the charge that a capacitor can hold
its size, distance between plates and the material used
define kirchoffs law
in circuits in series: kirchoffs law states that voltage is shared between resistors, and current remains the same
in circuits in parallel: kirchoffs law states that the voltage across resistors remains the same, and the current is split
capacitors are frequency dependent in their opposition to current flow, this opposition is know as….
reactance
what is bridged impedance matching
when the load impedance is equal to or greater than 10 times the output impedance
Capacitance is measured in ________.
farads (F)
what does RMS stand for
root means squared
what do conductors do
they are materials that allow electrons to flow easily
what does RMS stand for
Root Means Square
what is the SI unit of charge and what is it measured in
charge (Q) is measured in coulombs (C)
define DC
implies electrons flow in one direction only
what are inductors
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core.
define AC
alternating current, it implies flow of electrons in alternating directions
what does the power of one watt corrospond to
the conversion of 1 joule of energy per second
what are diodes
a diode is a semi conductor device, as they normally only allow current to travel in one direction
what do transformers do
they make it possible to step up or down voltage and current
what is the SI unit of current and what is it measured in
current (I) is measured in amperes (A)
what is voltage
the potential electrical difference between 2 points in circuit, or one point and a ground
what do semi conductors do
they allow current flow only under specific conditions
what are transistors
a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material usually with at least three terminals for connection to an external circuit.
what is the SI unit of energy and what is it measured in
energy (W) is measured in Joules (J)
what is an LCR circuit
a capacitor/ inductor/ resistor in series circuit
What is a capacitor?
a device used to store an electric charge, made of one or more pairs of conductors separated by an insulator (dielectric)
define energy, and what it is measured in
energy is the capacity for doing work, must have energy to accomplish work. Energy is measured in Joules
what does ohms law state
current is directly proportional to voltage and indirectly proportional to resistance
What type of current do we use in homes and other buildings?
AC
what is circuit ground
an electrical connection to the earth, a common return path in circuits
what does a current carrying conductor induce
a magnetic field around itself
what is a ground isolator
it disrupts the noise in ground loops
what is the output across the resistor in an LR circuit
a low pass filter
what do DI boxes do in terms of impedence
they lower the output impedance of devices such as electric guitars, bases etc.
what does EMF stand for
Electromotive Force, and causes electrons to flow
what happens when a capacitor is connected to an AC supply, with a high frequency
if the frequency is high enough, the capacitor will not have time to charge in either direction, and the opposition to current flow will be low
what does one joule correspond to
the amount of force needed to accelerate a mass of 1KG, 1 meter per second, squared
define resistance of a circuit
resistance is the opposition to current flow
how are the following charged:
neutrons, electrons and protons
neutrons are neutrally charged,
electrons are negatively charged,
protons are positively charged
what is a CR circuit
a capacitor and a resistor in circuit series
what is an atom, and what is it made up of
an atom is a fundamental piece of matter, and consists of protons, neutrons and electrons
what is the output across the capacitor in a CR circuit
a low pass filter
what is the SI unit of reactance and what is it measured in
reactance (x) is measured in ohms (Ω)
what is the SI unit of inductors and what is it measured in
inductors (L) is measured in henrys (H)
what are ground loop transformers
they break the connection of a dc circuit between components while passing the different signal of the line
what is charge
the concentration of electrons at a given circuit point
name examples of conductors
silver
copper
gold
aluminium
zinc
nickel
brass
what happens to the high frequencies across the inductor in an LCR circuit
the high frequencies will drop across it, and create a high pass filter
What is resistance? What unit of measurement is used?
opposition to current flow
measured in ohms (Ω)
what is ground loop
it occurs when 2 points in a circuit have a potential difference between them, and is a cause of noise and hum
what is the definition of work
it refers to an activity involving force and movement in the direction of force
what is impedance
the effective resistance of an electric circuit or component to alternating current arising from the combined effects of resistance and reactance
what is inductive reactance
Inductive reactance is the name given to the opposition to a changing current flow. This impedance is measured in ohms, just like resistance.
what do insulators do
they offer high resistance to current flow
