Law of Conservation of Energy

Name a device or gadget which converts mechanical energy to electrical energy.

Name a device or gadget which converts electrical energy to light energy.

Name a device or gadget which converts electrical energy to sound energy.

Name a device or gadget which converts mechanical energy to sound energy.

Name a device or gadget which converts sound energy to electrical energy.

What kind of energy transformation takes place in the following gadget?

Photoelectric cell.

What kind of energy transformation takes place in the following gadget?

Microphone.

State the law of conservation of energy. Prove that energy remains conserved for a freely falling mass $m$.

Mention how energy changes from one form to the other in a thermal power station.

Name the sequence of energy changes taking place in the production of electricity in a hydroelectric dam.

Two masses $\mathrm{m}$ and $2\mathrm{m}$ are dropped from heights $\mathrm{h}$ and $2\mathrm{h}$. On reaching the ground, which one will have more kinetic energy? Why?

Why does a nail become warmer when hammered into a plank?

An object of mass $10 \mathrm{kg}$ is dropped from a height of $20 \mathrm{m}$. Calculate the potential energy and kinetic energy of the object at various heights as mentioned in the data:

Show by calculations that the above data verifies the law of conservation of energy. (take $\mathrm{g}=10 \mathrm{m}/{\mathrm{s}}^2$ )

Describe the energy transformations that take place when a ball is thrown up in the air, reaches the maximum height, descends and finally hits the ground.

State and explain the law of conservation of energy. Explain with an example.

Name five gadgets which use electrical motors.

Name a device or gadget which converts light energy to chemical energy.

Name a device or gadget which converts mechanical energy to heat energy.