ELECTROMAGNETISM COMMON PROPERTIES OF ELECTROMAGETIC WAVES PROPERTIES AND USES OF IR RADIATION PROPERTIES AND USES OF UV RADIATION

3. arranged in order of increasing wavelength

4. 1)The electromagnetic waves of entire wavelength range do not
require any material medium for their propagation.
2) They all travel with the same speed in vacuum (or air) which is
same as the speed of light i.e., ., 3 x 108 m s-1
3) They exhibit the properties of reflection and refraction. In
refraction, when an electromagnetic wave passes from one medium
to the other, its speed and wavelength changes, but its frequency
remains unchanged.
4) These waves are not affected by the electric and magnetic
fields.
5) These waves are the transverse waves.

5. PROPERTIES AND USES OF INFRARED
1) They travel in straight lines with a speed equal to 3 x 108 m s-1 in
vacuum (or air).
2) They obey the laws of reflection and refraction.
3) They do not affect the ordinary photographic film. However, they affect
a specially treated photographic film.
PROPERTIES INFRARED RADIATION.

6. 4) They are absorbed by glass, but they are not absorbed
by rock-salt.

7. 5) They are detected by their heating property using a thermopile or a
blackened bulb thermometer. Its high dose may cause skin burns.

8. 6) They are less scattered by the atmosphere because of their long
wavelength ,so they can penetrate deep in atmosphere even in fog.

9. 1) The infrared radiations are used for therapeutic purposes
by doctors.
2) They are used in photography at night and also in mist
and fog because they are not much scattered, so they can
penetrate appreciably through it.
3) Infrared lamps are used in dark rooms for developing
photographs since they do not affect the photographic film
chemically, but they provide some visibility.
USES INFRARED RADIATION

10. 4) They are used as signals during war as they are not
visible and they are not absorbed much in the
medium.
5) They are used in remote control of
television and other gadgats.

11. properties and uses of ultraviolet radiation.
properties
1) Ultraviolet radiations can pass through quartz, but they are absorbed
by glass. The ultraviolet spectrum is therefore obtained by passing the
radiations through a quartz prism instead of a glass prism. For the
same reason the ultraviolet bulbs have the envelope made of quartz
instead of glass

12. 2) These radiations travel in a straight line with a speed of 3 x 108 m s-1
in air (or vacuum)
3) They are usually scattered by the dust particles present in the
atmosphere.

13. 4) They obey the laws of reflection and refraction.
5) They strongly affect the photographic plate as
they are chemically more active.

14. 6) They produce fluorescence on striking a zinc
sulphide screen.

15. 7) They cause health hazards like skin cancer if
our body is exposed to them for a long period.

16. uses of ultraviolet radiation.
1) For sterilising purposes.

17. 2) For detecting the purity of gems, eggs, ghee, etc.
3 ) In producing vitamin D in food of
plants and animals