P5 Revision

Question 1

What is a cell?

Answer 1

A cell pushes electrons around a complete circuit

Question 2

what is a switch

Answer 2

Allows current to be switched on or off

Question 3

What is an indicator

Answer 3

An indicator emits light as a signal when current passes through

Question 4

What is a diode?

Answer 4

A diode allows current to pass through in 1 direction only

Question 5

What does a light emitting diode do?

Answer 5

Emits light when current passes through in a forward direction

Question 6

What does an ammeter do

Answer 6

Measures electric current

Question 7

What does a fixed resistor do?

Answer 7

Limits current in a circuit

Question 8

What is a variable resistor?

Answer 8

allows current to be varied

Question 9

what is a fuse

Answer 9

melts or breaks the circuit when current exceeds a certain amount

Question 10

what is a heater

Answer 10

Heaters are designed to transfer energy from electric current to heat the surroundings

Question 11

what is a voltmeter

Answer 11

Measures potential difference

Question 12

charge flow =

Answer 12

current x time taken

Question 13

potential difference across a component =

Answer 13

energy transferred/ charge

Question 14

resistance =

Answer 14

P.d/ current

Question 15

Unit for P.d

Answer 15

Volts

Question 16

Unit for energy

Answer 16

Joules

Question 17

Unit for charge

Answer 17

Coulombs

Question 18

Unit for current

Answer 18

Amps

Question 19

Unit for power

Answer 19

Watts

Question 20

Ohms law?

Answer 20

The current through a resistor at constant temperature is directly proportional to potential difference across the resistor.

Question 21

what is a thermistor

Answer 21

A thermistor is a temperature dependent resistor

Question 22

What happens to resistance when temperature increases in a thermistor

Answer 22

Decreases

Question 23

What happens to resistance when light intensity increases in an LDR

Answer 23

Decreases

Question 24

Forward resistance in Diode?

Answer 24

Low

Question 25

Reverse resistance in diode?

Answer 25

High

Question 26

Total resistance :

Answer 26

R1 + R2

Question 27

What is direct current

Answer 27

Direct current is current which flows in 1 direction only

Question 28

What is alternating current?

Answer 28

Alternating current is current which repeatedly reverse flow of direction of charge

Question 29

What is a live wire

Answer 29

The live wire is connected directly to the generators of the electricity supply company .It carries current at high voltages (about 220−230V)

Question 30

What is a neutral wire

Answer 30

Neutral wires take current back from the consumer to the National Power Grid

Question 31

What are step up transformers?

Answer 31

Used by power stations to transfer electricity to the National Grid

Question 32

what are step down transformers?

Answer 32

Step down transformers deliver electricity to consumers such as homes and offices. Supplied at 230V

Question 33

Parts of a three pin plug

Answer 33

Earth Wire, Neutral wire, live wire and fuse box

Question 34

Colour of earth wire

Answer 34

Green and Yellow

Question 35

Colour of Neutral Wire

Answer 35

Blue

Question 36

Colour of Live Wire

Answer 36

Brown

Question 37

Why are pins made of brass and not copper

Answer 37

Brass because Brass is a good conductor and doesn't rust or oxidise

Question 38

Why are copper used for the wires?

Answer 38

Because it is a good conductor and bends easily

Question 39

Energy Transferred =

Answer 39

Power/ Time

Question 40

Power supplied

Answer 40

current x potential difference

Question 41

Power supplied to a resistor :

Answer 41

Current2 x Resistance

Question 42

When charge flows through a resistor...

Answer 42

energy is transferred to the resistor, and the resistor becomes hotter

Question 43

efficiency

Answer 43

its output power/ input power (x100)

Question 44

output power =

Answer 44

efficiency x input power