An electromagnetic wave of frequency 3.0 MHz passes from vacuum into a dielectric of relative permittivity 4.0 and μᵣ = 1. What happens to its frequency and wavelength?
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An electromagnetic wave of frequency 3.0 MHz passes from vacuum into a dielectric of relative permittivity 4.0 and μᵣ = 1. What happens to its frequency and wavelength?

G1 Physics · Accepted Answer

Step 1: The frequency of a wave is determined by the source and stays unchanged as the wave crosses a boundary. Step 2: The wave speed in a nonmagnetic dielectric is v = c/√εᵣ = c/2 for εᵣ = 4. Step 3: Because λ = v/f and f is unchanged, λ becomes one-half of its vacuum value. Final B. Final answer: (B) Wavelength halves; frequency is unchanged.