Electromagnetic Waves

The velocity of electromagnetic radiation in a medium of permittivity 0 and permeability 0 is given by

1. 1 0 0
2. 0 0
3. 0 0
4. 0 0

The electric and magnetic field of an electromagnetic wave are

1. in opposite phase and perpendicular to each other
2. in opposite phase and parallel to each other
3. in phase and perpendicular to each other
4. in phase and parallel to each other

If v, x and m represent the wavelengths of visible light, X-rays and microwaves respectively, then

1. m > x > v
2. m > v > x
3. v > x > m
4. v > m > x

We consider the radiation emitted by the human body. Which one of the following statements is true?

1. The radiation emitted is in the infra-red region
2. The radiation emitted only during the day
3. The radiation is emitted during the summers and absorbed during the winters
4. The radiation emitted lies in the ultraviolet region and hence is not visible

Which of the following rays are not electromagnetic waves?

1. X-rays
2. -rays
3. -rays
4. heat rays

The velocity of electromagnetic wave is parallel to

1. B E
2. E B
3. E
4. B

What is the cause of greenhouse effect?

1. infra-red rays
2. ultra violet rays
3. X-rays
4. radio waves.

Biological importance of ozone layer is

1. it stops ultraviolet rays
2. ozone layer reduces greenhouse effect
3. ozone layer reflects radio waves
4. ozone layer controls O2/H2 ratio in atmosphere

The frequency order for -rays (a), X-rays (b), UV rays (c) is

1. b > a > c
2. a > b > c
3. c > b > a
4. a > c > b