The shortest wavelength is for 

(1) $\gamma$-rays

(2) X-rays

(3) ultraviolet rays

(4) microwaves

An accelerated charge :

(1) emits an electromagnetic wave

(2) does not emit electromagnetic wave

(3) produces a gravitational field

(4) None of these

The electromagnetic radiations are in descending order of wavelength in the following sequences :

(1) infra-red waves, radio waves, X-rays, visible light rays

(2) Radio-waves, infra-red waves, visible light rays, X-rays

(3) Radio waves, visible light rays, infra-red waves, X-rays

(4) X-rays, visible light rays, infra-red wave, radio-waves

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.

Which of the following are not electromagnetic waves?

(1) cosmic rays

(2) gamma rays

(3) microwaves

(4) X-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 wave impedance of free space is

(1) 0 $\Omega$

(2) 376.6 $\Omega$

(3) 1883 $\Omega$

(4) 3776 $\Omega$