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1.7.1a Energy stores and energy transfers

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Question 22
a.

The principle of conservation of energy states that energy can neither be created nor destroyed. What, then, does happen to the electrical energy supplied to a device such as a projector or a laptop?

[1]
b.

A multimedia projector is switched on to screen a presentation. During this time, 500 kJ500\text{ kJ}500 kJ of electrical energy is supplied to the device.

The energy division for the projector is as follows:

  • Electrical energy input = 500 kJ500\text{ kJ}500 kJ
  • Light energy output = 15 kJ15\text{ kJ}15 kJ
  • Sound energy output = 5 kJ5\text{ kJ}5 kJ

Find the total useful energy provided for the audience to see and hear the presentation.

[1]
c.

Suggest what happens to the rest of the energy supplied.

[1]
d.

Calculate the amount of energy involved in (b)(ii).

[1]
e.

Comment on the efficiency of this projector.

[2]
Markscheme

1.7.1a Energy stores and energy transfers Questions

  1. IGCSE
  2. /Physics
  3. /1.7.1a Energy stores and energy transfers

229 exam-style questions on CIE IGCSE Physics 1.7.1a Energy stores and energy transfers. Each one has a worked solution and a mark scheme showing where the marks go.

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