CIE iGCSE Co-Ordinated Science P1.6.3 Energy resources Exam Style Questions Paper 4
Question
Fig. 3.1 shows a wind turbine used to generate electricity.
(a) State one advantage of generating electricity using wind turbines.
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(b) The wind turbine contains an alternating current (a.c.) generator.
On Fig. 3.2, sketch a graph of output voltage against time for the a.c. generator when the wind turbine is turning at a constant speed.
(c) A step-up transformer is used to increase the voltage from the generator.
Describe the construction of a basic step-up transformer.
You may include a labelled diagram to aid your description.
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(d) The wind exerts a pressure of 7200Pa on each blade of the wind turbine.
Each blade has a surface area of 90m2.
Calculate the force exerted by the wind on each turbine blade.
force = ……………………………………………… N
(e) The wind turbines produce a low-pitch sound when they turn.
(i) State the minimum frequency of sound which can be heard by a healthy human ear.
frequency = ……………………………………………. Hz
(ii) Sound waves are longitudinal waves.
Describe, in terms of oscillations and energy transfer, what is meant by a longitudinal wave.
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▶️Answer/Explanation
Ans: 3(a) does not release CO2 / does not release greenhouse gases / does not contribute to global warming / climate change / no fuel costs / renewable / AVP ;
3(b) sinusoidal waveform ;
constant time period and amplitude ;
3(c) (soft) iron core ;
two coils wrapped around the same core ;
number of turns on primary less than secondary / number of turns on secondary more than primary ;
3(d) evidence of F = P × A or 7200 × 90 ;
650 000 (N) ;
3(e)(i) 20 (Hz) ;
3(e)(ii) (direction of) oscillations are parallel to direction of energy transfer ;