Embibe Experts Solutions for Chapter: Electromagnetic Waves, Exercise 1: AMU-AT (B.Tech.) 2017

The magnetic field amplitude of an electromagnetic wave is $2\times {10}^{-7} \mathrm{T}$. Its electric field amplitude if the wave is travelling in free space is

In electromagnetic waves travelling in vacuum
(i) The electric field $E$ is always perpendicular to the magnetic field $B$.
(ii) The cross product $\overrightarrow{E}\times \overrightarrow{B}$ always gives the direction in which the waves travel.
iii) The field $E$ and $B$ vary sinusoidally.
iv) There is a phase difference of $\frac{\pi }{2}$ between $E$ and $B$.
The correct statement(s) is (are)

Consider the following
(i) Submarine communications
(ii) A.M. radio
(iii) Shortwave ratio
(iv) Radar

Arrange the above in increasing frequency of the waves associated with them

The electric field associated with an electromagnetic wave in vacuum is given by $\overrightarrow{E}=40\cos \left(kz-6\times {10}^{8}t\right)\hat{i},$ where $E,z$ and $t$  are $\mathrm{volt} {\mathrm{m}}^{-1}$, metre and second respectively. The value of wave vector $k$ is

The electromagnetic wave used in $\mathrm{LASIK}$ eye surgery is

The charging current for a capacitor at any instant is $0.78 \mathrm{A}$. The displacement current across the capacitor plates at that instant is