Two plane electromagnetic waves in vacuum have equal electric-field amplitudes but frequencies f and 2f. Their classical average intensities are in the ratio:
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Question

Two plane electromagnetic waves in vacuum have equal electric-field amplitudes but frequencies f and 2f. Their classical average intensities are in the ratio:

G1 Physics · Accepted Answer

For a classical plane electromagnetic wave in vacuum, I = ½cε₀E₀². The expression depends on field amplitude but does not explicitly depend on frequency. Since the two waves have the same E₀, their average intensities are equal. Therefore the ratio is 1:1. Correct option: C.