O-LevelPhysicsMagnetism5054/21 · May/June 2019 · Q75 Marks

Fig. 7.1 shows part of a torch. The torch does not contain a battery. [Figure 7.1] The torch is shaken and this causes the magnet to move backwards and forwards through the coil.

(a)(i)Explain why an electromotive force (e.m.f.) is induced in the coil when the magnet moves.[2]
(a)(ii)State one way to increase the e.m.f. induced.[1]
(b)(i)The current in the coil is used to produce light from a light-emitting diode (LED). In the space below, draw the circuit symbol for an LED.[1]
(b)(ii)An LED is a more efficient source of light than a filament lamp. Explain what this statement means.[1]

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Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

[1] magnetic field / flux mentioned
[1] change in field / flux (in coil) or field (lines) cut coil / wire
[1] more turns or stronger magnet or move magnet faster
[1] correct symbol
[1] converts more of the input energy / power into light / useful energy / power or less energy / power wasted with same input energy / power or in same time or same input power / energy / current gives more light/less energy wasted / power wasted / heat / greater power out or less input power / energy gives same output power / energy

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