Light with an average flux of \(20~\text{W/cm}^2\) falls on a non-reflecting surface at normal incidence having a surface area \(20~\text{cm}^2\). The energy received by the surface during time span of \(1\) minute is:
1. \(12\times 10^{3}~\text{J}\)
2. \(24\times 10^{3}~\text{J}\)
3. \(48\times 10^{3}~\text{J}\)
4. \(10\times 10^{3}~\text{J}\)

The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is: (\(c\) = speed of electromagnetic waves)

The EM wave with the shortest wavelength among the following is:

The magnetic field in a plane electromagnetic wave is given by:
\(B_y = 2\times10^{-7} \text{sin}\left(\pi \times10^{3}x+3\pi\times10^{11}t\right )T\)${}_{}$
The wavelength is:
1. \(\pi\times 10^{3}~\text{m}\)
2. \(2\times10^{-3}~\text{m}\)
3. \(2\times10^{3}~\text{m}\)
4. \(\pi\times 10^{-3}~\text{m}\)

For a transparent medium relative permeability and permittivity, \(\mu_r\) and \(\varepsilon_r\) are \(1.0\) and \(1.44\) respectively. The velocity of light in this medium would be:

The ratio of the amplitude of a magnetic field to the amplitude of an electric field for an electromagnetic wave propagating in a vacuum is equal to:

The electric field of an electromagnetic wave in free space is given by –
$\overrightarrow{E}=10$ $\cos$ $({10}^{7}t+kx)$ $\hat{j}$ $V/m$, where t and x are in seconds and metres respectively. It can be inferred that:

(a) The wavelength λ is 188.4 m
(b) The wave number k is 0.33 rad / m
(c) The wave amplitude is 10 V / m
(d) The wave is propagating along + x direction

Which one of the following pairs of statements is correct?

1. (a) and (b)

2. (b) and (c)

3. (c) and (d)

4. (a) and (c)

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

If \(\lambda_{\mathrm{v}}, \lambda_{\mathrm{x}},\) and\(\lambda_\mathrm{m}\) represent the wavelengths of visible light, x-rays and microwaves respectively, then:
1. \( \lambda_{\mathrm{m}}>\lambda_{\mathrm{x}}>\lambda_{\mathrm{v}} \)
2. \( \lambda_\mathrm{v}>\lambda_\mathrm{m}>\lambda_\mathrm{x } \)
3. \( \lambda_\mathrm{v}>\lambda_\mathrm{x}>\lambda_\mathrm{m }\)
4. \(\lambda_{\mathrm{m}}>\lambda_{\mathrm{v}}>\lambda_{\mathrm{x}}\)

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