Electricity

Question 1

State the equation that links charge, current and time

Answer 1

Charge = Current x Time

Question 2

What are the units for charge?

Answer 2

Coulombs, C

Question 3

What are the units for current?

Answer 3

Amps, A

Question 4

What are the units for time?

Answer 4

Seconds, s

Question 5

State the equation that links current, potential difference and resistance

Answer 5

Potential difference = Current x Resistance

Question 6

What are the units for potential difference?

Answer 6

Volts, V

Question 7

What are the units for resistance?

Answer 7

Ohms, Ω

Question 8

What is a series circuit?

Answer 8

A circuit with only one pathway for current to flow

Question 9

What is a parallel circuit?

Answer 9

A circuit with more than one pathway for current to flow

Question 10

What happens to current in a series circuit?

Answer 10

It is the same anywhere in the circuit

Question 11

What happens to potential difference in a series circuit?

Answer 11

It is shared between the components

Question 12

What is the resistance in a series circuit?

Answer 12

The total resistance is the sum of the resistance of each component

Question 13

What happens to current in a parallel circuit?

Answer 13

It is shared between the different pathways

Question 14

What happens to potential difference in a parallel circuit?

Answer 14

It is the same for all components

Question 15

What is the resistance in a parallel circuit?

Answer 15

The total resistance is the less than the component with the smallest resistance

Question 16

Describe the relationship between current and potential difference for a resistor

Answer 16

Current and potential difference are directly proportional

Question 17

Describe the resistance through a diode

Answer 17

Resistance is low in one direction, but very high in the opposite direction

Question 18

Describe the relationship between resistance and temperature for a thermistor

Answer 18

As temperature increases, resistance decreases

Question 19

Describe the relationship between resistance and temperature for an LDR

Answer 19

As light intensity increases, resistance decreases

Question 20

Name two sources of direct current

Answer 20

Battery and cell

Question 21

Name a source of alternating current

Answer 21

Mains

Question 22

What is direct current?

Answer 22

Current that flows in one direction only

Question 23

What is alternating current?

Answer 23

Current that continually changes direction

Question 24

What is the potential difference of mains electricity?

Answer 24

230V

Question 25

What is the frequency of mains electricity?

Answer 25

50Hz

Question 26

Define power

Answer 26

The rate at which energy is transferred OR the rate at which work is done

Question 27

What are the units for power?

Answer 27

Watts, W

Question 28

What are the units for energy?

Answer 28

Joules, J

Question 29

What are the units for work done?

Answer 29

Joules, J

Question 30

What equation links energy, power, time?

Answer 30

Power = Energy / Time

Question 31

What equation links power, time and work done?

Answer 31

Power = Work done / Time

Question 32

What equation links current, potential difference and power?

Answer 32

Power = Potential difference x Current

Question 33

What equation links current, resistance and power?

Answer 33

Power = (Current)2 x Resistance

Question 34

What colour is the live wire?

Answer 34

Brown

Question 35

What colour is the neutral wire?

Answer 35

Blue

Question 36

What colour is the Earth wire?

Answer 36

Green and yellow striped

Question 37

What is the function of the live wire?

Answer 37

Carries the potential difference at 230V

Question 38

What is the function of the neutral wire?

Answer 38

Completes the circuit, is at 0V

Question 39

What is the function of the Earth wire?

Answer 39

Safety wire, carries the potential difference if the appliance becomes live

Question 40

Why does touching the live wire cause electric shock?

Answer 40

The difference in potential difference between our body and the live wire is 230V, this forces a current through the body and causes electric shock

Question 41

What equation links charge, energy and potential difference?

Answer 41

Energy = Charge x Potential difference

Question 42

What is the National Grid?

Answer 42

A network of cables and transformers that transport electricity from power stations to consumers

Question 43

How do step-up transformers affect potential difference and current?

Answer 43

Increase potential difference and decrease current

Question 44

How do step-down transformers affect potential difference and current?

Answer 44

Decrease potential difference and increase current

Question 45

Why is electricity transmitted at very high potential difference?

Answer 45

This reduces current, which reduces heating of the wires, which reduces energy loss

Question 46

Why is electricity delivered to homes at lower potential difference?

Answer 46

So it is safer for people to use

Question 47

Draw the symbols for each component: Open switch, closed switch, lamp, cell, battery, voltmeter, ammeter, fuse, diode, variable resistor, thermistor, resistor, LED, LDR

Answer 47