A microwave oven needs its turntable for a reason: 2.45 GHz waves bouncing between the metal walls set up a standing wave, so the antinodes get scorching while the nodes stay nearly cold. When the source itself moves, the rings bunch up ahead of it and stretch out behind, so an observer hears a higher frequency as it approaches and a lower one as it recedes: the Doppler effect. In every kind of wave, however many times the frequency rises, the wavelength falls by exactly the same factor, because the product of the two is always the propagation speed v.
A microwave oven needs its turntable for a reason: 2.45 GHz waves bouncing between the metal walls set up a standing wave, so the antinodes get scorching while the nodes stay nearly cold. When the source itself moves, the rings bunch up ahead of it and stretch out behind, so an observer hears a higher frequency as it approaches and a lower one as it recedes: the Doppler effect. In every kind of wave, however many times the frequency rises, the wavelength falls by exactly the same factor, because the product of the two is always the propagation speed v.
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