Class 11 Physics Work Energy Power Various forms of energy

Various forms of energy

Heat: The work done by friction is not ‘lost’, but is transferred as heat energy


Chemical Energy:

  • Chemical energy arises from the fact that the molecules participating in the chemical reaction have different binding energies.
  • If the total energy of the reactants is more than the products of the reaction, heat is released and the reaction is said to be an exothermic reaction.
    Example- When you freeze water you remove energy from water to lower its temperature and its phase is changed to ice, so it is a exothermic process
  • If the reverse is true, heat is absorbed and the reaction is endothermic.
    Example- While melting the ice you provide energy to the ice to increase its tempreature and change its phase to water, so it is a endothermic process.

Electrical Energy: The flow of electrical current causes bulbs to glow, fans to rotate and bells to ring. Energy is associated with an electric current.


Nuclear Energy:

  • The energy released from the nuclear reactions, either fission or fusion, is called as nuclear energy.
  • Nuclear fusion and fission are manifestations of the equivalence of mass and energy.
  • In fusion light atom nuclei like Hydogen fuse to form a bigger nucleus whose mass is less than the sum of the masses of the reactants.
  • In fission, a heavy nucleus like uranium 235U92 , is split by a neutron into lighter nuclei. Once again the final mass is less than the initial mass and the mass difference translates into energy.

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