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 $\Omega$

The frequency 1057 MHz of radiation arising from two close energy levels in hydrogen belongs to

(1) radio waves

(2) infrared waves

(3) micro waves

(4) $\gamma$-rays

The wave associated with 2.7 K(kelvin) belongs to

(1) radio waves

(2) micro waves

(3) ultraviolet ways

(4) infrared waves

The penetration power of X-ray increases with the increases in its :

(1) velocity

(2) intensity

(3) frequency

(4) wavelength

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