Chapter 1 Flashcards
Electronic Components and Fundamental Circuits Principles
What are resistors?
Electronic components that resist or control the flow of electric currents in electrical appliances and devices.
Types of Resistors
- Fixed
- Variable
What is a potentiometer?
A type of small variable resistor which can have its resistance value changed with a screwdriver
What are resistors used for?
To prevent damage to devices/systems or to ensure they operate within safe limits.
What are resistors normally composed of?
Metal and Carbon
What happens to heat when a current flows through a resistor?
It dissipates
What are capacitors?
Electronic components that store and release electrical energy in a electric field, which preserves voltage
What are capacitors used for?
They are used in power supplies to provide a temporary backup of electrical energy and in many devices to stabilise voltage levels.
What are inductors?
Electronic components that temporarily store energy in a magnetic field.
What does a inductor consist of?
A conducting material such as copper wrapped around a core made from a magnetic material.
What is the purpose of inductors?
Inductors store energy in a magnetic field when current flows through their coils. They resist changes in the flow of electric current.
Capacitors vs Inductor
Inductors store energy in a magnetic field
Capacitors store energy in a electrical field
Inductors conserve current
Capacitors conserve voltage
What is a diode?
Devices that allow electrical current to flow in one direction while blocking it in the other direction.
Where are diodes used?
- Power supplies
- DC-to-DC converters
- Power inverters
- Switches in digital logic circuits
What are LEDs?
Tiny electric bulbs that use small amounts of
electricity, they emit light when electrical current passes through them.
What does LEDs stand for?
Light Emitting Diodes
What are Op-amps?
Electronic devices that amplify the difference in voltage between the two inputs (inverting and non-inverting). They make small changes in voltage much larger.
What does Op-amps mean?
Operational Amplifier
Where are Op-amps used?
In signal amplification
What are switches?
Devices that open or close an electrical circuit. When you flip a switch, it either allows electricity to flow through (closed) or blocks it (open).
What is Ohm’s law?
Voltage is directly proportional to the current provided R remains constant.
The current is inversely proportional to the resistance provided the voltage remains constant.
Mathematical expression of Ohm’s law
Voltage = Current * Resistance or V = I R
What is the relationship between current and resistance?
Current is inversely proportional to resistance
Symbol and Unit of Voltage
V and Volt
Symbol and Unit of Current
I and A (Ampere)
Symbol and Unit of Resistance
R and Ω (Ohm)
What is voltage?
Electrical pressure that causes charged electrons to flow through a conducting
loop, enabling them to do work such as illuminating a light bulb.
What are the types of voltage?
- direct (DC)
- alternating (AC)
What type of polarity does AC and DC have?
DC maintains the same polarity whilst with AC the polarity changes direction periodically.
What is polarity?
The direction of the current
What is a DC power supply?
An electrical device that is capable of generating a constant voltage that a direct voltage needs.
What is the current?
The rate of charged particles (electrons) through an electric circuit
How does the electric current flow in a circuit?
The conventional flow of an electric current is from the positive terminal towards the negative terminal of a battery or power supply.
How to work out the resistance in a parallel circuit?
1/Rₜ = 1/R₁ + 1/R₂ + 1/R₃
or
V/Rₜ = V/R₁ + V/R₂ + V/R₃
What is the voltage divider rule?
A way to determine voltage values across resistors when placed in series
Equation for the voltage divider rule
V₁ = R₁ / (R₁ +R₂) x Vₜ
V₂ = R₂ / (R₁ + R₂) x Vₜ
What is the current divider rule?
A method to determine current values through resistors when they are placed in parallel.
Equation for the current divider rule
I₁ = (R₂ / (R₁ + R₂)) x Iₜ
I₂ = (R₁ / (R₁ + R₂)) x Iₜ
When is the current divider rule not used directly?
If the circuit contains more than two resistors in parallel
What is Kirchhoff’s Current Law?
The sum of the currents flowing through all the wires that meet at a node or point in a circuit is equal to zero.
Flowing ways is negative
Flowing towards is positive
Example. I₁ - I₂ + I₃ + I₄ = 0
For Kirchhoff’s current law describe how the currents flowing from and away from the node are presented?
The current flowing towards the node is taken to be positive and that flowing away from the node to be negative.
What is Kirchhoff’s Voltage Law?
The sum of the voltages within any loop in a circuit is equal to the sum of the products of the currents and resistors in the various parts of the loop.
Equation of Kirchhoff’s Voltage Law
V₁ - I₁ R₁ - (I₁ - I₂) x R₂ = 0
(I₁ - I₂)R₂ - V₂ - I₂R₃ - I₂R₄ - I₂R₅ = 0
Define Electrical Power and an example
The rate of change of energy
i.e. the change of electrical energy with time.
Symbol and Unit of Electrical Power
P and Watt (W)
Equation for Electrical Power
P = VI
P= I²R
P = V² / R
