The figure shows a parallel plate capacitor being charged by a battery. If X and Y are two closed curves then during charging, $\oint \overrightarrow{B}.d\overrightarrow{l}$ is zero along the curve:

   

1.	X only
2.	Y only
3.	Both X & Y
4.	Neither X nor Y

Which colour of light has the longest wavelength?

1. violet

2. red

3. blue

4. green

Choose the correct option:

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

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

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 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

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

In an electromagnetic wave, if the electric field oscillated sinusoidally with an amplitude of 48 V$m^{-1}$, then the RMS value of the oscillating magnetic field will be:

1. $1.6\times {10}^{-8}$ $T$

2. $1.6\times {10}^{-9}$ $T$

3. $144\times {10}^{-8}$ $T$

4. $11.3\times {10}^{-8}$ $T$

The sun delivers ${10}^{3}W/m^2$ of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimensions 8 m$\times$20 m will be:

1. $2.56\times {10}^4$ $W$

2. $6.4\times {10}^5$ $W$

3. $4.0\times {10}^5$ $W$

4. 1.6$\times {10}^5$ $W$