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Energy resources and energy transfers

Energy resources and energy transfers

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Question 43

The following electrical devices are used in an automated commercial greenhouse:

  • A ventilation extractor fan
  • B soil heating cable
  • C LED grow-lamp
  • D warning buzzer
a.

(i) Which device is designed to transfer electrical energy primarily to kinetic energy? (ii) Which device is designed to transfer electrical energy primarily to thermal energy?

[2]
b.

In all these devices, energy is conserved. Explain what is meant by the law of conservation of energy.

[2]
c.

(i) The LED grow-lamp (C) has an efficiency of 45%. Explain what this means. (ii) If the LED grow-lamp has a total input energy of 1500 J:

  1. Calculate the useful energy output.
  2. Calculate the wasted energy output.
  3. Describe how these energy transfers are represented on a labelled Sankey diagram (including arrow widths and directions).
[6]
Markscheme

Energy resources and energy transfers Questions

  1. IGCSE
  2. /Physics
  3. /Energy resources and energy transfers

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