Write magnitude and dimensional formula of $\frac{1}{{\sqrt {{\mu _0}{ \in _0}} }}$

A plane electromagnetic wave propagating in the direction of the unit vector $\hat{ n }$ with a speed $c$ is described by electric and magnetic field vectors $E$ and $B$, respectively. Which of the following relations (in $SI$ units) between $E$ and $B$ can be ruled out on dimensional grounds alone?

Equation of light wave, normally incident on a surface is $B = \left( {100nT} \right)\sin (2\pi ({10^{15}}t – \left( {3 \times {{10}^{ – 7}}} \right)x) + \frac{\pi }{6})$ .Find intensity of light on that surface …$W/m^2$

This question has Statement $-1$ and Statement $-2$ . Of the four choices given after the statements, choose the one that best describes the two statements

Statement $-1$ : Sky wave signals are used for long distance radio communication. These signals are in general, less stable than ground wave signals

Statement $-2$ : The state of ionosphere varies from hour to hour, day to day and season to season

What physical quantity is the same for $X-$rays of wavelength $10^{-10} \;m ,$ $red$ light of wavelength $6800\; \mathring A$ and radiowaves of wavelength $500 \;m ?$