If the frequency of an E.M. wave is 10 MHz, then its wavelength is:
1.  30 m
2.  300 m
3.  3 m
4.  none of the above

The frequency order for \(\gamma\) - rays (\(b\)), X – rays (\(a\)), and UV – rays (\(c\)) is:

The biological importance of the ozone layer is:

Which of the following has the minimum wavelength?
1. X-rays
2. Ultraviolet rays
3. γ-rays
4. Cosmic rays

What is the cause of “Greenhouse effect”?

1. Infra-red rays

2. Ultraviolet rays

3. X-rays

4. Radio waves

The velocity of electromagnetic waves is parallel to:

1. $\overrightarrow{\mathrm{B}}\times \overrightarrow{\mathrm{E}}$

2. $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$

3. $\overrightarrow{\mathrm{E}}$

4. $\overrightarrow{\mathrm{B}}$

If ${\mathrm{\lambda }}_{\mathrm{v}},$ ${\mathrm{\lambda }}_{\mathrm{x}}$, and ${\mathrm{\lambda }}_{\mathrm{m}}$ represent the wavelengths of visible light, x-rays and microwaves respectively, then:

1. ${\lambda }_{\mathrm{m}}>{\lambda }_{\mathrm{x}}>{\lambda }_{\mathrm{v}}$

2. ${\lambda }_v>{\lambda }_m>{\lambda }_x$

3. ${\lambda }_v>{\lambda }_x>{\lambda }_m$

4. ${\lambda }_{\mathrm{m}}>{\lambda }_{\mathrm{v}}>{\lambda }_{\mathrm{x}}$