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Electromagnetic Waves

Section: Physics

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Question : 3 of 19

Marks: +1, -0

The ratio of the magnitudes of the electric field and

10^8

times the magnetic field of a plane electromagnetic wave is

[AP EAPCET 23 May 2025 S1]

$\;1: 3$
$\;3: 1$
$\;1: 1$
$\;1: \sqrt{3}$

Solution:

The electric field (

E_0

) and magnetic field (

B_0

) in a plane electromagnetic wave have a special relationship.

We know that

\;\frac{E_0}{B_0}=c

where

c

is the speed of light, which is

3 \times 10^8\,\text{m/s}

.

If we compare

E_0

to

10^8

times

B_0

, we get:

\;\frac{E_0}{10^8 B_0} = \;\frac{E_0}{B_0} \times \;\frac{1}{10^8}

Now substitute

c

for

\;\frac{E_0}{B_0}: \;\frac{E_0}{10^8 B_0} = \;\frac{3 \times 10^8}{10^8} = 3

So, the answer is:

\;\frac{E_0}{10^8 B_0}=3

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