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Current Electricity

Question

A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the directions of its electric and magnetic field vectors? If the frequency of the wave is 30 MHz, what is its wavelength?

Solution

Given,
Plane EM wave travels in vacuum along z-direction.
Frequency of the wave = 30 MHz

\vec{E} and \vec{B}

lie in x-y plane and are mutually perpendicular.

Since,

C = vλ

we have,

Wavelength of the EM wave,

λ = \frac{c}{v} = \frac{3 \times 10^{8}}{30 \times 10^{6}} = 10 m .