Electromagnetic radiation
1
Choose the right answer
1
The speed of electromagnetic radiations in vacuum is 3X 108 m/s
2
Infrared radiation are used in long distance photography
QII Fill in the blanks
1 Electric and magnetic fields in electromagnetic wave are mutually perpendicular each
other
2 The range of wave length of visible light is 4X10-7-7X10-7
3 The rays used to show bone structure is X – rays
Q III
Match the following
A
B
1 Micro waves
Hertz
2 Infra red radiation
William Herschell
3 X-rays
Willam Rontgen
4Gamma rays
Henry Becquerel
5Ultraviolet radiation
J.W.Ritter
Q IV
Answer the following
1 What is electromagnetic radiation?
Ans An alternating electric field produce an alternating magnetic field ; this magnetic field
Produce an electric field. The two field sustain each other and a disturbance that is a wave
propagate through the medium perpendicular to the two field. This wave is called an
electromagnetic radiation
2Draw a neat diagram of electromagnetic wave?
Answer page no 263 fig 20.4
3 List the properties of electromagnetic wave ?
I)
All the properties of electromagnetic wave travel at the speed of light i.e 3x108m/s in
vacuum
2) They do not need any material medium for their propagation
3) Electromagnetic waves are three dimensional transverse waves
Q 4 Explain the electromagnetic spectrum with a neat diagram?
The orderly arrangement of electromagnetic waves according to their frequency or
wavelength is known as electromagnetic spectrum. The entire range of electromagnetic
spectrum is divided into different region with different names. The range of electromagnetic
waves varies from 102km to about 100km
For diagram refer page no 264 fig 20.5
Q 5 Write uses of the following
a) Radio waves -Radio waves of shorter length are used in communication system like
raders and TV broad casting . Radio waves of longer wave length are used in radio broad
casting
b) Micro waves i) Used in ovens for cooking
Ii) Used for analysis of atomic and molecular structure
c)Ultraviolet radiation i)Used to test purity of gems
ii)Used in the treatment of rickets,
diseases of bones and skin iii) Used up by our body in the synthesis of vitamin –D
d) X –rays i) Used to show bone structure
ii)Used to detect foreign bodies like coins,
pins, bullets etc in animal and human bodies
e) Infra red radiation - Used in long distance photography ii)They are used in remote
control of TV
f)Gamma rays are i) Used in the treatment of cancer ii) Used in gamma rays microscope
iii )Used in radiography