A rescue team uses the hand generator in Fig. 1 to charge a radio when no mains supply is available. Turning the handle rotates a coil between magnet poles....
Question 1 Report
A rescue team uses the hand generator in Fig. 1 to charge a radio when no mains supply is available. Turning the handle rotates a coil between magnet poles. The radio circuit then provides sound and receives radio waves.
(a) What energy store is decreased by the person turning the handle? [1]
(b) Calculate the charge transferred when a current of 0.40 A flows for 30 s.
Use the equation: charge = current × time. [2]
(c) Give one way to increase the potential difference induced by the generator. [1]
(d) Describe the energy transfers from the handle to the radio speaker. [2]
Answer Details
A generator transfers energy by rotating a coil in a magnetic field. The induced electrical output can power the radio.
- (a) The person's chemical energy store, in the muscles/body, decreases. [1]
- (b) \[Q=It=0.40\ \text{A}\times30\ \text{s}=12\ \text{C}\] [2]
- (c) Turn the handle faster, use stronger magnets, or use more turns on the coil. Any one increases the induced potential difference. [1]
- (d) Chemical energy is transferred to the kinetic energy of the turning coil [1]. The generator transfers energy electrically, then the speaker transfers electrical energy to sound energy. [1]
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