A plane electromagnetic wave of frequency $500\, MHz$ is travelling in vacuum along $y-$direction. At a particular point in space and

time, $\overrightarrow{ B }=8.0 \times 10^{-8} \hat{ z } \;T$. The value of electric field at this point is

(speed of light $\left.=3 \times 10^{8}\, ms ^{-1}\right)$

$\hat{ x }, \hat{ y }, \hat{ z }$ are unit vectors along $x , y$ and $z$ direction.

Which scientist discarded postulate of ether? 

An EM wave from air enters a medium. The electric fields are $\overrightarrow {{E_1}}  = {E_{01}}\hat x\;cos\left[ {2\pi v\left( {\frac{z}{c} – t} \right)} \right]$ in air and $\overrightarrow {{E_2}}  = {E_{02}}\hat x\;cos\left[ {k\left( {2z – ct} \right)} \right]$ in medium, where the wave number $k$ and frequency $v$ refer to their values in air. The medium is nonmagnetic. If $\varepsilon {_{{r_1}}}$ and $\varepsilon {_{{r_2}}}$ refer to relative permittivities of air and medium respectively, which of the following options is correct?

Given below are two statements:

Statement $I$: Electromagnetic waves carry energy as they travel through space and this energy is equally shared by the electric and magnetic fields.

Statement $II$: When electromagnetic waves strike a surface, a pressure is exerted on the surface.In the light of the above statements, choose the most appropriate answer from the options given below:

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 $500 \;m ?$