Question

The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to
A.Reciprocal of speed of light in vacuum
B.The ratio of magnetic permeability to the electric susceptibility of vacuum
C.Unity
D.The speed of light in vacuum

Answer 1

To solve this question firstly we should understand the concept of magnetic field and electric field and all the related information. We will also study the relation between the electric field and magnetic field. And by this information, we will easily approach our answer.

Complete answer:
A magnetic field is a vector quantity that describes the magnetic influence or an electric charge of another moving charge. A charge that is a magnetic field that is perpendicular to its own velocity and magnetic field.
Electric fields surround an electric charge and exert force on the charge of electric fields attracting or repelling it.
Electric field and magnetic field both are interrelated to each other and both are components of electromagnetic waves.

We know that,
$\Rightarrow \,\,C\, = \,\dfrac{{{E_0}}}{{{B_0}}} \\\ \Rightarrow \,\,\dfrac{{{B_0}}}{{{E_0}}}\, = \,\dfrac{1}{C} \\\$

Therefore, the ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave in a vacuum is equal to the reciprocal of speed of light.

Hence, the correct option is A - Reciprocal of speed of light in vacuum

Note: The way in which electric field and magnetic field interact each other is described in Maxwell and Lorentz force law. The force exerted by the electric field is much stronger than the force exerted by the magnetic field.
Also, Magnetic energy density is equal to the electrical energy density, in an electromagnetic wave.