Why does a room heater have a polished reflector at the back?

_____ is not necessary on radiation for heat transmission.

Give reason for the following:

The water pipe in a solar water heater is bent into the shape as given in the picture.

Define the following term:

Land breeze

Define the following terms:

Infrared radiation

Give reason for the following:

A hot air balloon rises up in the sky. 

A utensil, which is made of thick copper base, is placed on the gas burner to heat up water in it.

a) Describe briefly how heat is transferred:

ii) Spread through water in the utensil.

Define the following term:

Convection current

A utensil, which is made of thick copper base, is placed on the gas burner to heat up water in it.

Explain why water would boil faster when a lid is placed on the utensil.