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 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

A larger parallel plate capacitor, whose plates have an area of 1 $m^2$, 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 $\mu A$

2. 11 $\mu A$

3. 2.2 $\mu A$

4. 1.1 $\mu A$

If an electromagnetic wave of frequency f = 3 MHz passes from vacuum into a dielectric medium with relative permittivity K= 4.0, then:

The maxwell's equation:

$\oint \overrightarrow{B}.\overrightarrow{dl}={\mu }_0\left(i+{\epsilon }_0.\frac{d{\varphi }_E}{dt}\right)$ is a statement of :