A capacitor is made of two circular plates each of radius \(12~\text{cm}\) and separated by \(5.0~\text{cm}\). The capacitor is being charged by an external source. The charging current is constant and equal to \(0.15~\text{A}\). The displacement current across the plates is:
1. \(0\)
2. \(0.14~\text{A}\)
3. \(0.16~\text{A}\)
4. \(0.15~\text{A}\)

Which physical quantity does not change in vacuum for X-rays?

The electric field part of an electromagnetic wave in vacuum is,
\(\vec{E}=(3.1 \mathrm{~N} / \mathrm{C}) \cos \left[(1.8~ \mathrm{rad} / \mathrm{m}) y+\left(5.4 \times 10^8 ~\mathrm{rad} / \mathrm{s}\right) \mathrm{t}\right] \hat{i}\).
What is the frequency of the wave?
1. \(5.7\times 10^{7}~\text{Hz}\)
2. \(9.3\times 10^{7}~\text{Hz}\)
3. \(8.6\times 10^{7}~\text{Hz}\)
4. \(7.5\times 10^{7}~\text{Hz}\)
 

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. $\mathrm{\gamma }$-rays

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 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)

Which statement is correct for X-rays and gamma rays?

The magnetic field amplitude of an electromagnetic wave is $2\times {10}^{-\mathrm{7 }}$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. \(\frac{10}{6}~\mathrm{Vm^{-1}}\)$\frac{\mathrm{}}{}$

4. None of these

Choose the correct option: