Skip to content

Course home

Sign up

1.7 Energy, work and power

EasyMedium
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444
Question 47
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 Energy, work and power Questions

  1. IGCSE
  2. /Physics
  3. /1.7 Energy, work and power

533 exam-style questions on CIE IGCSE Physics 1.7 Energy, work and power, covering 1.7.1a Energy stores and energy transfers, 1.7.1b Conservation of energy, 1.7.1c Kinetic and gravitational potential energy, 1.7.2 Work done, 1.7.3 Energy resources, 1.7.3a Energy resources and electricity generation, 1.7.3b Nuclear fusion as an energy source, 1.7.3c Efficiency of energy transfer, and 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.

Question bank