electricity

Question 1

function of: cell

Answer 1

Provides electrical energy to charges in a circuit.

Question 2

function of: battery

Answer 2

Provides electrical energy to charges in a circuit.

Question 3

function of: diode

Answer 3

Allows current to flow through it in one direction only

Question 4

function of: resistor

Answer 4

Used in circuits to set current.

Question 5

function of: variable resistor

Answer 5

Used to vary the size of current in a circuit.

Question 6

function of: fuse

Answer 6

A fuse melts to break the circuit if the current is too large.

Question 7

function of LED:

Answer 7

convert electrical energy directly into light

Question 8

function of: lamp

Answer 8

heats up when an electric current passes through it and produces light

Question 9

function of: switch

Answer 9

turn electric circuits ON and OFF

Question 10

function of: voltmeter

Answer 10

measure the voltage, or potential variation, between two locations

Question 11

function of: ammeter

Answer 11

measure the current in a circuit

Question 12

function of: thermistor

Answer 12

measure the temperature of a device

Question 13

function of: LDR

Answer 13

detect light levels

Question 14

The rate of flow of charge in a circuit =

Answer 14

Current

Question 15

The difference in potential between two points of a circuit. Causes a current to flow =

Answer 15

Potential Difference / voltage.

Question 16

the amount of electricity travelling through a circuit =

Answer 16

Charge

Question 17

Anything that slows the flow of charge around a circuit.
Resistance is usually caused by electrons colliding with
ions in a material =

Answer 17

Resistance

Question 18

A circuit with a single loop of wire =

Answer 18

Series Circuit

Question 19

A circuit with two or more loops (branches) of wire =

Answer 19

Parallel Circuit

Question 20

Describe the difference between a series circuit and a parallel circuit.

Answer 20

• A series circuit contains only one loop of wire.
• A parallel circuit contains two or more loops (branches) of wire.

Question 21

charge flow (c) =

Answer 21

current (A) x time (s)

Question 22

Potential Difference (V) =

Answer 22

Current (A) x Resistance (Ω)

Question 23

at a constant temperature is ….

Answer 23

directly proportional

Question 24

As the current increases, the temperature of filament increases therefore ….

Answer 24

the resistance of the filament lamp increases.

Question 25

resistance (Ω) =

Answer 25

potential difference (v) / current (A)

Question 26

Describe how the currents in a series circuit and a parallel circuit differ.

Answer 26

* Series circuit – same current at any point of the loop. * Parallel circuit – the total current through the whole circuit is the sum of the currents in each loop

Question 27

What does A.C stand for?

Answer 27

Alternating current.

Question 28

What does D.C stand for?

Answer 28

Direct current.

Question 29

Describe the difference between an alternating potential difference and direct potential difference.

Answer 29

* An alternating potential difference will go from positive to negative repeatedly. * Producing an alternating current in a circuit. * A direct potential difference will stay either positive or negative, but not change sign. * Producing a direct current in a circuit.

Question 30

What is the frequency and potential difference of mains electricity in the U.K?

Answer 30

Frequency 50Hz Potential difference 230V

Question 31

Live wire (Brown) =

Answer 31

Carries alternating potential difference from the supply.

Question 32

Neutral wire (Blue) =

Answer 32

Completes the circuit.

Question 33

Earth wire (Yellow/Green) =

Answer 33

Safety wire to stop appliance becoming live

Question 34

Explain why a live wire may be dangerous even when a switch in the mains circuit is open.

Answer 34

A person could complete the circuit to ground getting electrocuted.

Question 35

Power (W) =

Answer 35

Potential Difference (V) x Current (A)

Question 36

Power (W) =

Answer 36

(current)2 (A) x Resistance (Ω)

Question 37

As with any energy transfer, some energy will be transferred usefully and some energy will be ....

Answer 37

wasted

Question 38

Energy transferred (J) =

Answer 38

Power (W) × Time (s)

Question 39

Energy transferred (J) =

Answer 39

Charge flow (C) x Potential difference (V)

Question 40

Step-up transformers are used to ....

Answer 40

Increase the potential difference and decrease the current.

Question 41

Step-down transformers are used to ....

Answer 41

increase the current and decrease the potential difference.

Question 42

Describe what would happen if two like charged particles were placed near each other.

Answer 42

Two like charges would repel away from each other.

Question 43

A balloon is rubbed on a jumper. The balloon becomes positively charged. Explain why the balloon gains a negative charge.

Answer 43

* Electrons move from the jumper to the balloon. * So there are more negative charges on the balloon than positive charges.

Question 44

What is an electric field?

Answer 44

the space around a charged object that will exert a force upon another charged object that is placed there