Q.21)-The energy emitted by the sun is due to
  • Chemical reaction
  • Nuclear fission
  • Nuclear fusion
  • All of the above
Q.22)-How much mechanical work must be done to completely melt 1 gram of ice at 0 degree celsius?
  • 4.2J
  • 80J
  • 336J
  • 2268J
Q.23)-A bullet is fired from a rifle which recoils after firing.The ratio of kinetic energy of the rifle to that of the bullet is
  • Zero
  • One
  • Less than one
  • More than one
Q.24)-Direct conversion of solar energy with the use of a photovoltaic cell results in the production of
  • Optical energy
  • Electrical energy
  • Thermal energy
  • Mechanicla energy
Q.25)-A photo-electric cell converts
  • Mechanical energy to electric energy
  • Heat energy to mechanical energy
  • Light energy to chemical energy
  • Light energy to electrical energy
Q.26)-A stone is dropped from the roof of a house towards the ground.The kinetic energy of the stone will be maximum
  • Just after it is dropped
  • When it is just on the half-way
  • Just before it touches the ground
  • When it touches the ground
Q.27)-A dynamo is used to convert
  • Mechanical energy into electrical energy
  • Electrical energy into mechanical energy
  • Electrical energy into magnetic energy
  • Magnetic energy into mechanical energy
Q.28)-When a body falls from an aeroplane, there is increase in its
  • Kinetic energy
  • Mass
  • Acceleration
  • Potential energy
Q.29)-In a water lifting electric pump, we convert
  • Electrical energy into potential energy
  • Kinetic energy into electrical energy
  • Kinetic energy into potential energy
  • Electrial energy into kinetic energy
Q.30)-The device used to convert solar energy into electricity is
  • Photovoltaic cell
  • Daniell cell
  • Electrochemical cell
  • Galvanic cell