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The magnetic field of a plane electromagnetic wave is given by B = 100 x 10⁻⁶ * sin[2*pi * 2 x 10¹⁵ (t - x/c)]. Taking the speed of light as 3 x 10⁸ m/s, what is the maximum (amplitude) electric field of this wave?

1. 4 x 10⁴ N/C
2. 4.5 x 10⁴ N/C
3. 6 x 10⁴ N/C
4. 3 x 10⁴ N/C

Correct answer: 3 x 10⁴ N/C

Solution

The amplitude of the magnetic field is B0 = 100 x 10⁻⁶ = 1 x 10⁻⁴ T. For a plane EM wave, E0 = c*B0 = 3 x 10⁸ * 1 x 10⁻⁴ = 3 x 10⁴ N/C.

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