In an electromagnetic wave in free space the root mean square value of the electric field is $E_{rms}=6$ V/m. The peak value of the magnetic field is:

1. 1.41$\times {10}^{-8}T$

2. $2.83\times {10}^{-8}T$

3. $0.70\times {10}^{-8}T$

4. $4.23\times {10}^{-8}$ $T$ $$

The electric field associated with an electromagnetic wave in vacuum is given by \(E=40 \cos \left(k z-6 \times 10^8 t\right)\), where \(E\), \(z\), and \(t\) are in volt/m, meter, and second respectively. The value of the wave vector \(k\) would be:
1. \(2~\text{m}^{-1}\)
2. \(0.5~\text{m}^{-1}\)
3. \(6~\text{m}^{-1}\)
4. \(3~\text{m}^{-1}\)     

The ratio of the amplitude of the magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to

(1) the speed of light in vacuum

(2) reciprocal of speed of light in vacuum

(3) the ratio of magnetic permeability to the electric susceptibility of vacuum

(4) unity

The decreasing order of the wavelength of infrared, microwave, ultraviolet and gamma rays is

(1) gamma rays, ultraviolet, infrared, microwaves

(2) microwaves, gamma rays, infrared, ultraviolet

(3) infrared, microwave, ultraviolet, gamma rays

(4) microwave, infrared, ultraviolet, gamma rays