Question

Some pairs of devices and associated energy changes are given below:

i) Electric generator - Mechanical to electrical

ii) Electric motor - Electrical to mechanical

iii) Diesel engine - Light to electrical

iv) Solar cell - Chemical to mechanical

Which of the above pair / s is/are correctly matched?

1. i and ii
2. i and iii
3. ii and iv
4. iii and iv

Answer 1

Correct Answer - Option 1 : i and ii

The correct answer is statement 1 and 2.

• Electric generator - Mechanical to electrical
• Electric motor - Electrical to mechanical

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• Electric Motor ➔ Fleming’s left-hand rule
• Electric Generator ➔ Electromagnetic Induction ➔ Fleming’s right-hand rule

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• Electric Generator
  • ​Generators do not create electricity.
  • They use mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit.
  • This flow of electrons constitutes the output electric current supplied by the generator. 
  • The modern-day generators work on the principle of electromagnetic induction discovered by Michael Faraday.
  • Thus an electric motor is a device that converts electrical energy into mechanical energy. 
• Electric motors
  • A simple motor has a DC power source.
  • An electric motor is a rotating device that converts electrical energy to mechanical energy.
  • An electric motor consists of a rectangular coil of insulated metallic wire.
  • The coil is placed between the two poles of a magnetic field.
  • On supplying a magnetic field it rotates and produces mechanical energy.

• The Diesel engine
  • The Diesel engine is an internal combustion engine.
  • In these engines, the fuel is injected into a combustion chamber.
  • On ignition by the high temperature of the air in the chamber, the air gets compressed.
  • Thus these engines only compress the air and not the fuel.
  • When injected into the combustion chamber, the Diesel fuel undergoes spontaneous ignition, which provides the force to accelerate the vehicles.
• Solar cells or photovoltaic cells
  • Solar cells or photovoltaic cells are made based on the principle of the photovoltaic effect.
  • They convert sunlight into direct current (DC) electricity.