Q. A plane Electromagnetic Wave of frequency 30 MHz travels in free space along the $x$-direction. The electric field component of the wave at a particular point of space and time E=6 Vm$^{-1}$ along $y$-direction. Its magnetic field component $B$ at this point would be
A) $2 \times 10^{- 8}$ T along $z$-direction
B) $6\ \times 10^{- 8}$ T along $x$-direction
C) $2\ \times 10^{- 8}$ T along $y$-direction
D) $6\ \times 10^{- 8}$ T along $z$-direction
Explanation
(a) The frequency of Electromagnetic Wave along $y -$direction
$v\ = 30\ MHz$
The electric field component of the wave along $y$-direction.
$E = \ 6\ Vm^{- 1}$
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In Electromagnetic, the ratio of the amplitudes of electric and magnetic field is always constant and it is equal to velocity of the Electromagnetic Waves.
$ie,$ $\frac{E}{B} = c$
or $B\ = \ \frac{E}{c} = \frac{6}{3\ \times \ 10^{8}}$
or $B = \ 2\ \times \ 10^{- 8}\ T$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.