Uses and Dangers of Electric Heating

Section 1 of 8Advantages of electric heating

Appliances built to heat

• Appliances built to heat Kettles, ovens, toasters and domestic heaters rely on the heating effect to do their job.
• In a kettle, electrical work is transferred to the thermal store of the water.

Simple and direct

• Simple and direct A heating element is a short length of high-resistance wire, so no moving parts or fuel are needed.

Easy to control

• Easy to control The heat output can be varied or switched off immediately by controlling the current.

Section 2 of 8Disadvantages of electric heating

Wasted energy

• Wasted energy Thermal energy lost from filament lamps, motors and computers is not useful and lowers efficiency.

Fire risk

• Fire risk Too much current in poor-quality or damaged wiring can make it extremely hot and start a fire.
• Faulty motors can also produce sparks and excessive heat.

Burn risk

• Burn risk Hot elements, lamps and overheated cables can burn anyone who touches them.

Section 3 of 8Weighing it up

Device	Is the heat useful?	Comment
Kettle	Yes	Nearly all the energy is transferred to the water as intended.
Toaster	Yes	The element glows to toast the bread.
Filament lamp	Mostly no	Most of the energy heats the surroundings instead of giving light.
Laptop	No	Heat must be removed with fans to prevent damage.

Section 4 of 8Reducing the danger

1

Use cables of the correct thickness and good quality for the current they must carry.

2

Fit a fuse or circuit breaker that cuts off the supply when the current is too large.

3

Do not overload sockets with several high-power appliances.

4

Allow ventilation around appliances that give off heat.

Section 5 of 8Writing an evaluation answer

1

State the device or situation clearly, for example a kettle, a filament lamp or a damaged cable.

2

Give at least one advantage and one disadvantage of the heating effect in that situation.

3

Explain each point, linking it to energy: useful energy in the kettle is transferred to the thermal store of the water, whereas wasted energy in the lamp heats the surroundings.

4

Write a conclusion that weighs the two sides, such as: heating is essential in a heater but is a drawback in any device meant to give light or movement.

5

Finish with a safety comment if relevant, such as a fuse or the correct cable thickness.

Section 6 of 8Safety devices and good practice

Staying safe with electric heating

Fuses and circuit breakers

• Fuses and circuit breakers These cut the current when it exceeds a safe value, so the wiring cannot overheat and start a fire.

Earth wire and insulation

• Earth wire and insulation Plastic insulation around cables and an earth wire protect users if a fault makes a metal case live.

Sensible use

• Sensible use Never cover heaters, never overload an extension lead, and replace frayed cables straight away.

Section 7 of 8Key terms

Term	Meaning
Heating effect	Energy transferred to a thermal store when a current passes through a resistance.
Heating element	A high-resistance wire designed to become hot when a current flows.
Efficiency	The proportion of the energy supplied that is transferred usefully.
Fuse	A safety device containing a thin wire that melts and breaks the circuit if the current is too high.

Section 8 of 8Exam technique

1

Describing the heat from a filament lamp as 'useful' - it is the wasted output.

2

Giving only advantages or only disadvantages when the question asks you to evaluate.

3

Saying that a fire is caused by 'too much voltage' - the hazard is too much current through poor wiring.

4

Forgetting to mention the energy store, for example thermal store of the water in a kettle.

5

Giving a one-sided answer to an 'evaluate' question instead of weighing advantages against disadvantages.