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8.Electromagnetic waves
hard
A plane electromagnetic wave of frequency $35\ \mathrm{MHz}$ travels in free space along the $\mathrm{X}$-direction.
At a particular point (in space and time) $\overrightarrow{\mathrm{E}}=9.6\ \hat{\mathrm{j}} \mathrm{V} / \mathrm{m}$. The value of magnetic field at this point is:
A
$3.2 \times 10^{-8} \ \hat{\mathrm{k}} \mathrm{T}$
B
$3.2 \times 10^{-8}\ \hat{\mathrm{i}}$
C
$9.6 \ \hat{\mathrm{j}} \mathrm{T}$
D
$9.6 \times 10^{-8}\ \hat{\mathrm{kT}}$
(JEE MAIN-2024)
Solution
$ \frac{E}{B}=C $
$ \frac{E}{B}=3 \times 10^8$
$B =\frac{E}{3 \times 10^8}=\frac{9.6}{3 \times 10^8} $
$B =3.2 \times 10^{-8} \mathrm{~T} $
$\hat{B} =\hat{v} \times \hat{E} $
$ =\hat{i} \times \hat{j}=\hat{k}$
So,
$\overrightarrow{\mathrm{B}}=3.2 \times 10^{-8} \hat{\mathrm{k}} \mathrm{T}$
Standard 12
Physics
