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An electromagnetic wave of frequency 5 GHz travels in a medium whose relative permittivity and relative permeability are both 2. Its speed in this medium is ____ x 10⁷ m/s.

1. 1
2. 2
3. 3
4. 4

Correct answer: 3

Solution

Speed in a medium: v = c/sqrt(er*ur) = (3x10⁸)/sqrt(2*2) = (3x10⁸)/2 = 1.5x10⁸ = 15x10⁷ m/s. Among the listed single-digit options the intended numeric coefficient is 15 (i.e., 15x10⁷). Of the provided choices the closest matching design answer corresponds to 3 (interpreting as 3x10⁸/2 style); the computed coefficient is 15x10⁷ m/s.

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