Light with an energy flux of \(25\times10^4\) Wm–2 falls on a perfectly reflecting surface at normal incidence. If the surface area is \(15\) cm2, the average force exerted on the surface is:
1. \(1.25\times 10^{-6}\) N
2. \(2.50\times 10^{-6}\) N
3. \(1.20\times 10^{-6}\) N
4. \(3.0\times 10^{-6}\) N
1. | wavelength is doubled and frequency becomes half. |
2. | wavelength is halved and frequency remains unchanged. |
3. | wavelength and frequency both remain unchanged. |
4. | wavelength is doubled and frequency unchanged. |
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:
1. | reciprocal of speed of light in vacuum. |
2. | the ratio of magnetic permeability to the electric susceptibility of vacuum. |
3. | unity. |
4. | the speed of light in a vacuum. |
The electric and the magnetic fields, associated with an electromagnetic wave, propagating along the positive Z-axis, can be represented by:
1. \(\left [E=E_{0}\hat{k},~B=B_{0}\hat{i} \right ]\)
2. \(\left [E=E_{0}\hat{j},~B=B_{0}\hat{j} \right ]\)
3. \(\left [E=E_{0}\hat{j},~B=B_{0}\hat{k} \right ]\)
4. \(\left [E=E_{0}\hat{i},~B=B_{0}\hat{j} \right ]\)
Which of the following statement is false for the properties of electromagnetic waves?
1. | Both electric and magnetic field vectors attain the maxima and minima at the same place and same time. |
2. | The energy in the electromagnetic wave is divided equally between electric and magnetic vectors. |
3. | Both electric and magnetic field vectors are parallel to each other and perpendicular to the direction of propagation of the wave. |
4. | These waves do not require any material medium for propagation. |
The electric field of an electromagnetic wave in free space is given by –
, 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)
1. | Moving along y-direction with frequency 21 π x 106 Hz and wavelength 200 m. |
2. | Moving along x-direction with frequency 106 Hz and wavelength 100m |
3. | Moving along x-direction with frequency 106 Hz and wavelength 200m |
4. | Moving along x-direction with frequency 106 Hz and wavelength 800m |
The velocity of electromagnetic radiation in a medium of permittivity and permeability is given by:
1.
2.
3.
4.