A plane electromagnetic wave of frequency 40 MHz travels in free space in the x-direction. At some point and at some instant, the electric field E has its maximum value of 750 N/C in y-direction. The wavelength of the wave is:

Correct answer: C. 7.5 m

A. 3.5 m
B. 5.5 m
C. 7.5 m
D. 9.5 m

Explanation

We use the formula v=fλ. For EMW v=c=3×10⁸m/s. Rearranging for λ and putting values we get,λ = c/f = 3×10⁸/40×10⁸ = 7.5m.Hence, this option is correct.

Written and checked by Maryam Kashif, contributorLast updated 2 September 2026

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A plane electromagnetic wave of frequency 40 MHz travels in free space in the x-direction. At some point and at some instant, the electric field E has its maximum value of 750 N/C in y-direction. The wavelength of the wave is:

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