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Energy transfers

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Question 9

The following electrical appliances are used at an outdoor campsite:

  • A electric camping kettle
  • B electric air-pump
  • C LED floodlight
  • D electronic alarm buzzer
a.

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

[2]
b.

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

[2]
c.

(i) The LED floodlight has an efficiency of 42%. Explain what this means. (ii) If the LED floodlight 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).
[7]

Energy transfers Questions

  1. IGCSE
  2. /Physics
  3. /Energy transfers