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

The biological importance of the ozone layer is:

Which of the following has the minimum wavelength?
1. \(X\text-\)rays
2. Ultraviolet rays
3. \(\gamma\text-\)rays
4. Cosmic rays

What is the cause of “Greenhouse effect”?
1. Infra-red rays
2. Ultraviolet rays
3. \(X\text-\)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 \(\lambda_{v}, \lambda_{x},\) and \(\lambda_{m}\) represent the wavelengths of visible light, \(x\text-\)rays and microwaves respectively, then:
1. \( \lambda_{m}>\lambda_{x}>\lambda_{v} \)
2. \( \lambda_{v}>\lambda_{m}>\lambda_{x } \)
3. \( \lambda_{v}>\lambda_{x}>\lambda_{m }\)
4. \(\lambda_{m}>\lambda_{v}>\lambda_{x}\)