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According to the Doppler effect, what appears to happen when a light source moves closer to an observer?

The waves stretch and frequency appears to increase.

The waves stretch and frequency appears to decrease.

The electromagnetic waves appear more blue in color.

The electromagnetic waves appear more red in color.

Sally turns on her cellular telephone to speak to her friend who is located thousands of miles away. which of the following best describes how such a telephone is able to transmit and receive information? a. the cellular telephone transmits, receives, and encodes information using only sound waves. b. the cellular telephone transmits, receives, and encodes information using only electromagnetic waves. c. the cellular telephone transmits information by electromagnetic waves to a receiver which then encodes them and produces sound. d. the cellular telephone transmits information by sound waves to a receiver which then encodes them and produces electromagnetic waves.