Test Index

Electromagnetic Waves

Section: Physics

© examsnet.com

Question : 5 of 19

Marks: +1, -0

The magnitude of the electric field of a plane electromagnetic wave travelling in free space is E . If

\mu_0

\varepsilon_0

are respectively permeability and permittivity of the free space, then the magnitude of magnetic field of the wave is

[AP EAPCET 22 May 2025 S1]

$E \mu_0 \varepsilon_0$
$\frac{E}{\mu_0 \varepsilon_0}$
$E \sqrt{\mu_0 \varepsilon_0}$
$\frac{E}{\sqrt{\mu_0 \varepsilon_0}}$

Solution:

Step 1: Relationship between

E

and

B

in an electromagnetic wave

For a plane electromagnetic wave in free space,

E = c B

where

c

is the speed of light in free space.

Thus,

B = \frac{E}{c}

Step 2: Express

c

in terms of

\mu_0

and

\varepsilon_0

The speed of light is given by

c = \frac{1}{\sqrt{\mu_0 \varepsilon_0}}

Step 3: Substitute into expression for

B

B = \frac{E}{c} = E \sqrt{\mu_0 \varepsilon_0}

© examsnet.com

Go to Question:

Prev Question

Next Question