Which colour of light has the longest wavelength?
1. violet
2. red
3. blue
4. green
Choose the correct option:
1. | The radiation in increasing order of frequency are radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays. |
2. | The wavelength of colours in increasing order is violet, indigo, green, yellow, orange and red. |
3. | The speed of light is maximum in vacuum. |
4. | All options are correct. |
The magnetic field amplitude of an electromagnetic wave is T. Its electric field amplitude if the wave is travelling in free space is:
1. \(6~\mathrm{Vm^{-1}}\)
2. \(60~\mathrm{Vm^{-1}}\)
3. \(\frac{10}{6}~\mathrm{Vm^{-1}}\)
4. None of these
Which statement is correct for X-rays and gamma rays?
1. | X-rays are emitted from electronic transitions while gamma rays are emitted from nuclear transitions. |
2. | X-rays have less penetrating power in comparison to gamma rays, in general. |
3. | The frequency of gamma rays is more than the frequency of X-rays, in general. |
4. | All of the above. |
Consider an oscillator which has a charged particle oscillating about its mean position with a frequency of 300 MHz. The wavelength of electromagnetic waves produced by this oscillator would be:
1. 1 m
2. 10 m
3. 100 m
4. 1000 m
The figure shows a parallel plate capacitor being charged by a battery. If X and Y are two closed curves then during charging, is zero along the curve:
1. | X only |
2. | Y only |
3. | Both X & Y |
4. | Neither X nor Y |
If an electromagnetic wave propagating through vacuum is described by \(E_y= E_0 sin(kx-\omega t); ~B_z= B_0sin(kx-\omega t),\)then:
1. \(E_0k=B_0\omega\)
2. \(E_0B_0 = \omega k\)
3. \(E_0\omega= B_0k\)
4. \(E_0B_0= \frac{\omega}{k}\)
Which of the following is not an electromagnetic wave?
1. Radio wave
2. Micro wave
3. Cosmic rays
4. -rays
The speed of an electromagnetic wave in a medium of dielectric constant 2.25 and relative permeability 4 is approximately:
1. 1 x 108 m/s
2. 2.5 x 108 m/s
3. 3 x 108 m/s
4. 2 x 108 m/s
A larger parallel plate capacitor, whose plates have an area of 1 , separated from each other by 1 mm, is being charged at a rate of 25.8 V/s. If the plates have dielectric constant 10, then the displacement current at this instant is:
1. 25
2. 11
3. 2.2
4. 1.1