In a plane electromagnetic wave propagating in space has an electric field of amplitude $9\times {10}^3$ V/m, then the amplitude of the magnetic field is

(1) $2.7\times {10}^{12} T$

(2) $9.0\times {10}^{-3} T$

(3) $3.0\times {10}^{-4} T$

(4) $3.0\times {10}^{-5} T$

A radiowave has a maximum magnetic field induction of ${10}^{-4}$ T on arrival at a receiving antenna. The maximum electric field intensity of such a wave is

(1) zero

(2) $3\times {10}^4 V/m$

(3) $5.8\times {10}^{-9} V/m$

(4) $3.3\times {10}^{13 } V/m$

A capacitor is having a capacity of 2 pF. The electric potential across the capacitor is changing with a value of ${10}^{12}$ V/s. The displacement current is :

(1) 2 A

(2) 3 A

(3) 6 A

(4) 9 A

X-rays and $\gamma$-rays are both electromagnetic waves, which one of the following statements is true?

(1) in general, X-rays have a larger wavelength than that of $\gamma$-rays

(2) X-rays have a smaller wavelength than that of $\gamma$-rays

(3) $\gamma$-rays have smaller frequency than that of X-rays

(4) wavelength and frequency of X-rays are both larger than those of $\gamma$-rays.

The frequencies of X-rays, $\gamma$-rays and ultraviolet rays are respectively a, b and c. Then :

(1) a < b, b < c

(2) a > b, b > c

(3) a > b, b > a

(4) a < b, b > c

A plane electromagnetic wave of frequency 40 MHz travels in free space in the x-direction. At some point and at some instant, the electric field $\overrightarrow{E}$ has its maximum value of 750 N/C in y-direction. The wavelength of the wave is

(1) 3.5 m

(2) 5.5 m

(3) 7.5 m

(4) 9.5 m

The waves used in telecommunication are

(1) infrared

(2) visible light

(3) microwaves

(4) ultraviolet rays

The frequency \(1057~\text{MHz}\) of radiation arising due to electron transition between two close energy levels in hydrogen belongs to:
1. radio waves
2. infrared waves
3. microwaves
4. \(\gamma\text-\)rays

The shortest wavelength of X-rays emitted from an X-ray tube depends upon

(1) nature of the gas in the tube

(2) the voltage applied to the tube

(3) current in the tube

(4) nature of the target of the tube

X-rays are not used for radar purposes, because they are not 

(1) reflected by target

(2) partly absorbed by the target

(3) electromagnetic waves

(4) completely absorbed by the target