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Questions
A plane electromagnetic wave travels in the vacuum along the 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?
If the frequency of an electromagnetic wave travelling in a vacuum in the z-direction is 30 MHz, calculate its wavelength. Consider the speed of the wave as 3 × 108 m/s.
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Solution
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 and mutually perpendicular.
Frequency of the wave, v = 30 MHz = 30 × 106 s−1
Speed of light in a vacuum, c = 3 × 108 m/s
Wavelength of a wave is given as:
`lambda = "c"/"v"`
= `(3 xx 10^8)/(30 xx 10^6)`
= 10 m
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