The apparent change in frequency for a Dopper-shifted signal is due to an actual change in effective wavelength. Suppose a signal has a velocity of 100 m/s and produces a frequency of 10 cycles/s. Now suppose that somebody or something is "observing" this signal. If the receiver is not moving, then the receiver will receive 10 cycles/s. But suppose that the receiver is moving at 10 m/s. What would the (apparent) received frequency be? (Ignore any "relativistic" effects: you should be able to solve this problem with knowing that the velocity of a wave for a wave divided by length of wave is equal to the number of waves per second, and that velocity is relative.)

The apparent change in frequency for a Dopper-shifted signal is due to an actual change in effective wavelength. Suppose a signal has a velocity of 100 m/s and produces a frequency of 10 cycles/s. Now suppose that somebody or something is "observing" this signal. If the receiver is not moving, then the receiver will receive 10 cycles/s. But suppose that the receiver is moving at 10 m/s. What would the (apparent) received frequency be? (Ignore any "relativistic" effects: you should be able to solve this problem with knowing that the velocity of a wave for a wave divided by length of wave is equal to the number of waves per second, and that velocity is relative.)