NEET UG PHYSICS MCQ: ELECTROMAGNETIC WAVES

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Application +4 | -1

A plane electromagnetic wave, has frequency of

2.0 \times {10^{10}}Hz

and its energy density is

1.02 \times {10^{ - 8}}J/{m^3}

in vacuum. The amplitude of the magnetic field of the wave is close to (Take,

\frac{1}{{4\pi {\varepsilon _0}}} = 9 \times {10^9}\frac{{N{m^2}}}{{{C^2}}}

and speed of light

= 3 \times {10^8}m{s^{ - 1}}

)

View answer and explanation

Correct option: B

160 nT

Option B (160 nT) is correct because the energy density of an electromagnetic wave is related to the amplitude of the magnetic field by

u = \frac{B^2}{2\mu_0}

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