Question

(i) Why is the thin ozone layer on top of the stratosphere crucial for human survival ? Identify to which part of electromagnetic spectrum does this radiation belong and write one important application of the radiation. 

(ii) Why are infrared waves referred to as heat waves ? How are they produced ? What role do they play in maintaining the earth's warmth through the greenhouse effect ?

Answer 1

(i) It absorbs ultraviolet radiations from sun and prevents them from reaching on the earth's surface causing damage to life.

Identification : ultraviolet radiations

one correct application (= sanitization, forensics)

(ii) Water molecules present in most materials readily absorbs infra red waves. Hence, their thermal motion increases. Therefore, they heat their surroundings.

They are produced by hot bodies and molecules. Incoming visible light is absorbed by earth's surface and radiated as infrared radiations. These radiation are trapped by green house gases.