2: Electricity

Question 1

Alternating Potential Difference:

Answer 1

A continually oscillating current flow, which results in the potential difference across two points continually oscillating between a positive and negative value.

Question 2

Amperes (Amps):

Answer 2

The unit of current.
Attraction: A force pulling two opposite charges together, when they are brought near each
other.

Question 3

Coulomb:

Answer 3

The unit of charge.

Question 4

Diode:

Answer 4

A component that only allows current to flow through in the forward direction. They have very large resistances in the reverse direction.

Question 5

Direct Potential Difference:

Answer 5

A one-directional current flow.

Question 6

Earth Wire:

Answer 6

The green and yellow striped safety wire that prevents an appliance from becoming live.

Question 7

Electric Field Lines:

Answer 7

Lines representing an electric field, that point in the direction in which a positive charge would experience an electric force.

Question 8

Electric Field:

Answer 8

A region in which a charge will experience a non-contact, electric force. All
charged objects have an electric field around them, and this field is stronger the closer you are to the charge.

Question 9

Electrical Current:

Answer 9

The rate of flow of electrical charge. Its value is the same at any position in a single closed loop.

Question 10

Electrical Work:

Answer 10

When charge flows in a circuit, electrical work is said to be done.

Question 11

Filament Lamp:

Answer 11

A light emitting component consisting of an enclosed metal filament. Its resistance
increases as the filament’s temperature increases.

Question 12

Insulation:

Answer 12

The coating around power cables that prevents electrocution and is colour
coded to allow for easy identification.

Question 13

Light Dependent Resistor (LDR):

Answer 13

A light sensitive component whose resistance increases
as its temperature decreases.

Question 14

Live Wire:

Answer 14

The brown coloured wire that carries the alternating current from the supply in a
mains power supply.

Question 15

Mains Electricity:

Answer 15

An a.c supply, which in the UK has a frequency of 50Hz a value of 230V.

Question 16

Neutral Wire:

Answer 16

The blue coloured wire that completes the circuit in a mains power supply.

Question 17

Non-Contact Force:

Answer 17

A force experienced between two separated objects. Examples include gravity, and magnetic and electric forces.

Question 18

Ohmic Conductor:

Answer 18

A conductor whose current flow is directly proportional to the potential difference across it, when held at a constant temperature.

Question 19

Ohms:

Answer 19

The unit of resistance.

Question 20

Parallel: (Current, potential difference)

Answer 20

Components connected in parallel have the same potential difference across each component. The total current is equal to the sum of the currents flowing through each component.

Question 21

Potential Difference:

Answer 21

The product of a component’s resistance and the magnitude of current flow through it.

Question 22

Repulsion:

Answer 22

Caused when two like-charges are brought near each other.

Question 23

Resistance:

Answer 23

A measure of the opposition to current flow.

Question 24

Resistors in Parallel:

Answer 24

The total resistance is equal to the inverse of the sum of the inverses of the resistance of the parallel components. The total resistance of two parallel resistors is always less than the lowest individual resistor value.

Question 25

Resistors in Series:

Answer 25

The total resistance is equal to the sum of the resistances of the individual components.

Question 26

Series:

Answer 26

Components connected in series have the same current passing through each component but share the total potential difference of the power supply.

Question 27

Static Charge:

Answer 27

The charge caused by an imbalance of positive and negative charges in, or on, an object’s surface. It is often caused by electrons being rubbed from one surface onto another.

Question 28

Step-Down Transformers:

Answer 28

Devices found between the transmission cables and the
consumer that lower the potential difference of the power so it is at safe, usable levels.

Question 29

Step-Up Transformers:

Answer 29

Devices that increase the potential difference generated by a power station, so that the electrical power transmitted along the transmission cables is at a
higher potential.

Question 30

The National Grid:

Answer 30

The network of power stations, transformers and cables that connect
consumers to power stations.

Question 31

Thermistor:

Answer 31

A temperature dependent component, whose resistance increases as its temperature decreases.

Question 32

Volt:

Answer 32

The unit of potential difference.