Electricity

Question 1

Electrical Current

Answer 1

The electric charge transferred per second.

Question 2

Direct Current (d.c.)

Answer 2

The flow of current in one direction only.

Question 3

Alternating Current (a.c.)

Answer 3

The back and forth flow of current.

Current changes direction every fraction of a second.

Question 4

Electric Field

Answer 4

A force field that surrounds any electric charge.

Question 5

Potential Difference (Voltage)

Answer 5

The energy supplied to each coulomb of charge that passes through a power supply.

Question 6

Mains Voltage

Answer 6

The voltage supplied to any electrical device plugged into the mains.

In the UK, this is 230 V.

Question 7

Resistance

Answer 7

The opposition to current flow.

Question 8

Ohm’s Law

Answer 8

For a fixed temperature, the voltage across a conductor is directly proportional to the current passing through it.

Question 9

Ohmic Conductor

Answer 9

A component that obeys Ohm’s law.

Question 10

Non-Ohmic Conductor

Answer 10

A component that does not obey Ohm’s law.

Question 11

Series Circuit

Answer 11

A circuit in which all components are connected one after the other and there is only one path for the current to flow.

Question 12

Parallel Circuit

Answer 12

A circuit in which there is more than one path (branch) for the current to flow.

Question 13

Cell

Answer 13

A component used to power a circuit.

Question 14

Battery

Answer 14

A collection of two or more cells.

Question 15

Bulb/Lamp

Answer 15

A component that converts electrical energy to light energy.

Question 16

Switch

Answer 16

A component that allows a circuit to be turned on/off.

Question 17

Resistor

Answer 17

A component that opposes the flow of current.

Question 18

Variable Resistor

Answer 18

A component that allows the flow of current in a circuit to be changed.

Question 19

Ammeter

Answer 19

A component used to measure the current in a circuit.

Question 20

Voltmeter

Answer 20

A device used to measure the voltage across a circuit component.

Question 21

Ohmmeter

Answer 21

A device used to measure the resistance of a circuit component.

Question 22

Motor

Answer 22

A component that converts electrical energy to mechanical energy.

Question 23

D.C. Supply

Answer 23

A component that produces a constant voltage.

Question 24

A.C. Supply

Answer 24

A component that produces an alternating voltage.

Question 25

Diode

Answer 25

A component that allows current to flow in one direction only.

Question 26

Capacitor

Answer 26

A component that stores charge and therefore electrical energy.

Question 27

Microphone

Answer 27

A component that converts sound energy to electrical energy.

Question 28

Loudspeaker

Answer 28

A component that converts electrical energy to sound energy.

Question 29

Thermocouple

Answer 29

A component that converts heat energy into electrical energy.

Question 30

Solar/Photovoltaic Cell

Answer 30

A component that converts light energy into electrical energy.

Question 31

Thermistor

Answer 31

A temperature-dependent resistor whose resistance varies with temperature.

Question 32

LDR

Answer 32

A light-dependent resistor whose resistance varies with light intensity.

Question 33

LED (Light Emitting Diode)

Answer 33

A type of diode that converts electrical energy to light energy.

Question 34

Potential Divider

Answer 34

An arrangement of two or more resistors in series where the voltage from the supply splits across each resistor.

Question 35

Transistor

Answer 35

A semiconductor device that can be used as an electronic switch.

Question 36

NPN Transistor

Answer 36

A type of transistor that will switch on when the voltage across it reaches 0.7 V.

Question 37

MOSFET

Answer 37

A type of transistor that will switch on when the voltage across it reaches 2.0 V.

Question 38

Time Delay Circuit

Answer 38

A circuit, involving a capacitor and switch, in which there is a delay between switching on and the device turning on.

Question 39

Relay Switch

Answer 39

A device consisting of an electromagnetic coil and switch that can be used to control a high voltage circuit using a safe low voltage circuit.

Question 40

Electrical Power

Answer 40

The electrical energy transferred per second.

Question 41

Fuse

Answer 41

A safety device containing a thin wire which will break (melt) when too large a current flows through it.