Electricity

Question 1

Cell / battery

Answer 1

Provides the circuit with a source of potential difference. A battery is two or more cells.

Question 2

Switch

Answer 2

Turn the circuit on or off.

Question 3

Fixed resistor

Answer 3

A resistor limits the flow of current. A fixed resistor has a resistance it can’t change.

Question 4

Variable resistor

Answer 4

A resistor with a slider can be used to change its resistance. These are often used in dimmer switches and volume control.

Question 5

Thermistor

Answer 5

The resistance of a thermistor depends on its temperature. As its temperature increases, its resistance decreases.

Question 6

Light dependent resistor (LDR)

Answer 6

The resistance of an LDR depends on the light intensity. as light intensity increases its resistance decreases.

Question 7

Diode

Answer 7

A diode allows current to flow in one direction only. Current flows through the diode when it is in forward bias position. They are used to convert AC to DC current.

Question 8

Light emitting diode (LED)

Answer 8

This is equivalent to a diode and emits light when a current passes through it. These are used for aviation lights and displays.

Question 9

Ammeter

Answer 9

Used to measure the current in a circuit. connected in series with other components.

Question 10

Voltmeter

Answer 10

Use to measure the potential difference of an electrical component. connected in parallel with the relevant component.

Question 11

Potential difference

Answer 11

For electrical charge to flow through closed circuit, it must include a source of potential difference. Sources of potential difference include a cell, battery or electrical generator. A cell makes one end of the cell negative and the other end positive. This sets up a potential difference across the circuit sometimes known as voltage. The potential difference across a component in a circuit is defined as the energy transferred per unit charge flowing from one point to another.
Potential difference (Volts) = work done (Joules) / charge (coulomb)

Question 12

Electric current

Answer 12

Electric current is the flow of electrical charge and is measured in amps. The size of the current is the rate of flow of charge, how much charge passes through a point each second.
Charge (coulomb) = current (amps) x time (seconds)

Question 13

Current in a loop

Answer 13

Electrons are negatively charged so therefore they flow away from the negative terminal of the cell to the positive one.
Conventional current is defined as the flow of positive charge from the positive terminal of the cell to the negative one. This is opposite to the direction of electron flow because conventional current was used before the discovery of the electron.