A plane electromagnetic wave travels in vacuum along $z-$ direction. What can you say about the directions of its electric and magnetic field vectors? If the frequency of the wave is $30 \;MHz$, what is its wavelength in $m$?
A plane electromagnetic wave travels in vacuum along $z-$ direction. What can you say about the directions of its electric and magnetic field vectors? If the frequency of the wave is $30 \;MHz$, what is its wavelength in $m$?
The electromagnetic wave travels in a vacuum along the $z$ -direction. The electric field $(E)$ and the magnetic field $(H)$ are in the $x-y$ plane. They are mutually perpendicular.
Frequency of the wave, $v=30 MHz =30 \times 10^{6} s ^{-1}$
Speed of light in a vacuum, $c=3 \times 10^{8} m / s$
$\lambda=\frac{c}{v}$
$=\frac{3 \times 10^{8}}{30 \times 10^{6}}=10 m$
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${B_y} = \left( {2 \times {{10}^{ - 7}}} \right)\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)T$
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${B_y} = \left( {2 \times {{10}^{ - 7}}} \right)\sin \left( {0.5 \times {{10}^3}x + 1.5 \times {{10}^{11}}t} \right)T$
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$(b)$ Write an expression for the electric field.
About $5 \%$ of the power of a $100\; W$ light bulb is converted to visible radiation. What is the average intensity of visible radiation
$(a)$ at a distance of $1 \;m$ from the bulb?
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$(a)$ at a distance of $1 \;m$ from the bulb?
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