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