1. Motion, forces and energy

1.1 Physical quantities and measurement techniques

1.2 Motion

1.3 Mass and weight

1.4 Density

1.5.1 Effects of forces

1.5.2 Turning effect of forces

1.5.3 Centre of gravity

1.6 Momentum

1.7.1 Energy

1.7.2 Work

1.7.3 Energy resources

1.7.4 Power

1.8 Pressure

2. Thermal physics

2.1.1 States of matter

2.1.2 Particle model

2.1.3 Gases and the absolute scale of temperature

2.2.1 Thermal expansion of solids, liquids and gases

2.2.2 Specific heat capacity

2.2.3 Melting, boiling and evaporation

2.3.1 Conduction

2.3.2 Convection

2.3.3 Radiation

2.3.4 Consequences of thermal energy transfer

3. Waves

3.1 General properties of waves

3.2.1 Reflection of light

3.2.2 Refraction of light

3.2.3 Thin lenses

3.2.4 Dispersion of light

3.3 Electromagnetic spectrum

3.4 Sound

4. Electricity and magnetism

4.1 Simple phenomena of magnetism

4.2.1 Electric charge

4.2.2 Electric current

4.2.3 Electromotive force and potential difference

4.2.4 Resistance

4.2.5 Electrical energy and electrical power

4.3.1 Circuit diagrams and circuit components

4.3.2 Series and parallel circuits

4.3.3 Action and use of circuit components

4.4 Electrical safety

4.5.1 Electromagnetic induction

4.5.2 The a.c. generator

4.5.3 Magnetic effect of a current

4.5.4 Force on a current-carrying conductor

4.5.5 The d.c. motor

4.5.6 The transformer

5. Nuclear physics

5.1.1 The atom

5.1.2 The nucleus

5.2.1 Detection of radioactivity

5.2.2 The three types of nuclear emission

5.2.3 Radioactive decay

5.2.4 Half-life

5.2.5 Safety precautions

6. Space physics

6.1.1 The Earth

6.1.2 The Solar System

6.2.1 The Sun as a star

6.2.2 Stars

6.2.3 The Universe

IGCSE Physics 4.4 Electrical safety Question Bank

[Maximum number: 3]

Fig. 5.1 shows a kitchen tap that supplies instant boiling water.

Fig. 5.1

Cold water passes over an electric immersion heater inside the tap.
The boiling point of water is $100^{\circ} \mathrm{C}$ .

(a)

The metal tap is earthed and there is a fuse in the cable that connects the heater to the mains.
1. Explain how the earth wire protects the user.
2. Explain how the fuse protects the circuit.

[ 3 ]

[Maximum number: 1]

Four statements about safety when designing electrical products are listed.
1 If the outer casing is a conductor, it should be earthed.
2 If the outer casing is a conductor, it should not be earthed.
3 If the outer casing is an insulator, it should be earthed.
4 If the outer casing is an insulator, it should not be earthed.
Which statements are correct?

1 and 3

1 and 4

2 and 3

2 and 4

[Maximum number: 1]

Two electrical appliances are connected to the mains supply.
The cable connected to one appliance includes an earth wire.
The cable connected to the second appliance does not need an earth wire.
What is a reason for this difference?

One appliance has a metal case, but the other appliance does not.

One appliance is fitted with a fuse, but the other appliance is not.

One appliance is fitted with a switch, but the other appliance is not.

One appliance needs more current than the other appliance.

[Maximum number: 1]

Fig. 6.1 shows a shower that takes in cold water. The water passes through an electric water heater and emerges from the showerhead at a higher temperature.

Fig. 6.1

The power of the heater is 9000 W .

(a)

The shower is powered by a 230 V electricity supply.

[ 1 ]

(i)

Suggest a suitable rating for the fuse in the heater circuit.
fuse rating =

[ 1 ]

(a)

Another transformer is used in a school laboratory to step down a mains supply with a p.d. of 110 V to 12 V . This transformer is mounted in a metal case.

State and explain an essential safety feature required for this arrangement.

[ 2 ]

[Maximum number: 1]

An electric kettle has a metal casing. The cable for the kettle contains a wire that is connected to the earth pin of the plug.

Which danger does this guard against?

the cable to the kettle becoming too hot

the casing of the kettle becoming live

the casing of the kettle becoming wet on the outside

the casing of the kettle overheating

(a)

Fig. 7.2 shows an extension lead used to supply power to a 3 kW electric heater on a cool evening.

extension lead designed
for use with a 25 W lamp

Fig. 7.2
State and explain three dangers with this arrangement.
danger 1
danger 2
danger 3

[ 4 ]

[Maximum number: 6]

Fig. 8.1 shows a 240 V mains supply connected to an air-conditioning unit and a freezer. A fuse X is placed in the circuit as shown.

Fig. 8.1

The freezer has an operating power of 700 W .

(a)

The maximum operating current of the air-conditioning unit is 7.5 A .

Fuses of current rating $1 \mathrm{~A}, 3 \mathrm{~A}, 5 \mathrm{~A}, 10 \mathrm{~A}, 13 \mathrm{~A}$ and 30 A are available.
Suggest a suitable rating for fuse X. Give two reasons for your answer.
fuse rating
Reason 1

Reason 2

[ 3 ]

(b)

A fuse is made out of a short length of wire.

Explain why fuses of a higher rating are made of thicker wire.

[ 3 ]

[Maximum number: 1]

A domestic circuit includes a 30 A fuse. This protects the wiring if there is too much current in the circuit.

In which wire is the 30 A fuse positioned, and what does it do when it operates?

position

operation

live wire

disconnects the circuit

live wire

reduces the current to 30 A

neutral wire

disconnects the circuit

neutral wire

reduces the current to 30 A

[Maximum number: 1]

The metal cases of electrical appliances are connected to an earth wire.
Which statement is not correct?

The live wire may become loose and touch the metal case.

If the metal case becomes live, the earth wire conducts current to the ground.

The earth wire needs to have a high resistance.

Earthing metal cases helps prevent a person from receiving an electric shock.

0 selected

Question 5

Question 5(c)

Question 29

Question 30

Question 6

Question 6(a)

Question 6(a)(ii)

Question 7

Question 7(b)

Question 32

Question 7

Question 7(b)

Question 8

Question 8(b)

Question 8(c)

Question 33

Question 33