PHYSICS [1 Mark Question Answer]

Nuclear fusion is not being used to meet day to day energy needs because extremely high temperature and pressure is required to initiate the nuclear fusion. Such an extremely high temperature and pressure can not be achieved in daily life in a controlled way.

1. Bombardment of slow neutrons on heavy unstable nucleus (such as U-235).
2. A very high temperature of the order of millions of degree Calsius is required for nuclear fusion.

1. Nuclear fission is responsible for explosion of atom bomb.
2. Nuclear fusion is responsible for release of energy by the sun.

Methane is the major constituent of natural gas.

Geothermal energy.

Two forms of sea energy are:
1. Tidal energy
2. Wave energy

Anaerobic bacteria decomposes animal dung into biogas.

Solar Panel: The group of solar cells connected in specific pattern to produce desired potential difference and magnitude of current is called Solar Panel.

Solar cell.

The temperature within solar cooker rises to about 140°C.

Fossil fuels (coal, petrol, diesel etc.) are exhaustible i.e. if these are once finished can not be regenerated over a reasonable period of time. That is why fossil fuels are called non-renewable sources of energy.

Use of wood is renewable source, but is not advised to use, because saplings take a long time to become a tree.

Law of conservation of energy: According to law of conservation of energy- "energy is neither created nor destroyed in a system and sum total of energy remains same."

We should conserve the non-renewable sources of energy because if these sources once finished, cannot be regenerated over a reasonable period of time.