Applications of Heat Radiation

Applications of Heat Radiation

(1) Differential Air Thermo scope:

It is an important application of radiation of heat. It consists of two identical glass bulbs A & B which are connected by a narrow glass tubing have the shape of a U-tube. The tube consists of sulfuric acid (so as to absorb moisture of the air in. the tube). The space above the levels of the acid in the two arms of the tube contains air. When the bulbs are at the same temperature there is no difference in the level of the acid in the two limbs. The bulb A is coated with lamp black so that it may completely absorb the heat radiation falling on it. Now the bulb “A” is exposed to heat radiation. It absorbs whole of the radiation

falling of it. As a result the air in the bulb A gets heated, expands and presses down the acid in the limb. Thus we have a difference in the level of the liquid in the two limbs. This thermo scope is very sensitive and can detect radiation of very weak intensity for example the radiation coming from a distant candle.