Rankers Physics

Properties of EM Waves: Practice Problem & Solution

The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to: (2012 Mains)
The speed of light in vacuum
Reciprocal of speed of light in vacuum
The ratio of magnetic permeability to the electric susceptibility of vacuum
Unity

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Properties of EM Waves. Understanding the underlying formula is key to arriving at the correct answer below:

The speed of an electromagnetic wave in vacuum is related to the field amplitudes by $c = \frac{E_0}{B_0}$ . Rearranging this, we get the ratio of magnetic to electric field amplitude as $\frac{B_0}{E_0} = \frac{1}{c}$ . Therefore, it is the reciprocal of the speed of light in vacuum.

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