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CBSE Gujarat Board Haryana Board

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Class 10 Class 12
What is a good source of energy?

In general a good source of energy would be one,

(i) which would do a large amount of work per unit mass or volume
(ii) which would be easily accessible.
(iii) which can be easily stored and transported.
(iv) which is also reasonably economical.


A solar water heater cannot be used to get hot water on

  • a sunny day

  • a cloudy day

  • a hot day

  • a windy day


a cloudy day


Which of the following is not an example of a bio-mass energy source?

  • wood
  • gobar-gas
  • nuclear energy

  • coal


nuclear energy


What are the limitations of the energy that can be obtained from the oceans?

Energy from the oceans can be tapped in three different ways,

(i) Tidal energy.
(ii) Wave energy.
(iii) Ocean thermal energy.

(i) Tidal energy: Dams are constructed across the narrow openings in the sea and, the tidal energy can be harnessed using these methods. Such sites are limited and the electricity generated is not high enough to be commercially viable.

(ii) Wave energy:Kinetic energy of the air movement causes winf energy.
Such sites in the world are limited where the waves strike the shorelines with sufficient power.

(iii) Thermal energy: To convert ocean thermal energy into electricity, it is necessary that a difference of more than 20°C temperature between the surface waters and water at depths of 1000 metres is required. This process is not economical. 

Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
  • geothermal energy
  • wind energy
  • nuclear energy
  • bio-mass.


geothermal energy