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Question 47

A laboratory temperature chamber has a metal outer casing and contains two independent heating elements.

a.

The power rating of the temperature chamber is 520 W520\text{ W}520 W when running at full capacity. The chamber is connected to a 230 V230\text{ V}230 V mains supply.

State the equation linking power, current, and voltage.

[1]
b.

Calculate the current in the temperature chamber. Give your answer to two significant figures.

[2]
c.

Which of these mains fuses is the most suitable for the temperature chamber?

  • A: 1 A1\text{ A}1 A
  • B: 3 A3\text{ A}3 A
  • C: 5 A5\text{ A}5 A
  • D: 13 A13\text{ A}13 A
[1]
d.

The two heating elements inside the chamber can be configured to run in series or in parallel. Describe one advantage of each configuration in this appliance.

[2]
e.

Many electrical laboratory appliances are fitted with a three-core cable containing an earth wire.

Describe how an earth wire, together with a fuse, acts as a safety feature.

[3]
f.

Explain why this laboratory temperature chamber must be fitted with an earth wire, whereas a centrifuge with a plastic casing does not require one.

[2]
Markscheme

Electricity Questions

  1. IGCSE
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