A beam of light travelling along $X$-axis is described by the electric field $E _{ y }=900 \sin \omega( t - x / c )$. The ratio of electric force to magnetic force on a charge $q$ moving along $Y$-axis with a speed of $3 \times 10^{7}\,ms ^{-1}$ will be.

[Given speed of light $=3 \times 10^{8}\,ms ^{-1}$ ]

Even though an electric field $E$ exerts a force $qE$ on a charged particle yet the electric field of an $EM$ wave does not contribute to the radiation pressure (but transfers energy). Explain.

A particle of charge $q$ and mass $m$ is moving along the $x-$ axis with a velocity $v,$ and enters a region of electric field $E$ and magnetic field $B$ as shown in figures below. For which figure the net force on the charge may be zero :-

Plane microwaves from a transmitter are directed normally towards a plane reflector. $A$ detector moves along the normal to the reflector. Between positions of $14$ successive maxima, the detector travels a distance $0.13\, m$. If the velocity of light is $3 \times 10^8 m/s$, find the frequency of the transmitter.

The magnetic field in a travelling electromagnetic wave has a peak value of $20\ n T$. The peak value of electric field strength is......$Vm^{-1}$

In an electromagnetic wave, the amplitude of electric field is $1 V/m.$  the frequency of wave is $5 \times {10^{14}}\,Hz$. The wave is propagating along $z-$ axis. The average energy density of electric field, in $Joule/m^3$, will be