Topic 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.

Question 3

Attraction:

Answer 3

A force pulling two opposite charges together, when they are brought near each other.

Question 4

Coulomb:

Answer 4

The unit of charge.

Question 5

Diode:

Answer 5

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

Question 6

Direct Potential Difference:

Answer 6

A one-directional current flow.

Question 7

Earth Wire:

Answer 7

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

Question 8

*Electric Field Lines:

Answer 8

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

Question 9

*Electric Field:

Answer 9

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 10

Electrical Current:

Answer 10

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

Question 11

Electrical Work:

Answer 11

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

Question 12

Filament Lamp:

Answer 12

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

Question 13

Insulation:

Answer 13

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

Question 14

Light Dependent Resistor (LDR):

Answer 14

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

Question 15

Live Wire:

Answer 15

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

Question 16

Mains Electricity:

Answer 16

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

Question 17

Neutral Wire:

Answer 17

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

Question 18

Non-Contact Force:

Answer 18

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

Question 19

Ohmic Conductor:

Answer 19

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

Question 20

Ohms:

Answer 20

The unit of resistance.

Question 21

Parallel:

Answer 21

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 22

Potential Difference:

Answer 22

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

Question 23

Repulsion:

Answer 23

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

Question 24

Resistance:

Answer 24

A measure of the opposition to current flow.

Question 25

Resistors in Parallel:

Answer 25

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 26

Resistors in Series:

Answer 26

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

Question 27

Series:

Answer 27

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

Question 28

*Static Charge:

Answer 28

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 29

Step-Down Transformers:

Answer 29

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 30

Step-Up Transformers:

Answer 30

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 31

The National Grid:

Answer 31

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

Question 32

Thermistor:

Answer 32

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

Question 33

Volt:

Answer 33

The unit of potential difference.