A Clock with a Luminous Dial Is Moving Toward an Observer

question 103

Multiple Choice

A clock with a luminous dial is moving toward an observer at a speed that is a large fraction of the speed of light. Which of these will the observer measure?

• A) The light emitted by the clock will be shifted toward longer wavelengths compared to those seen by an observer moving with the clock.
• B) The light from the clock is approaching the observer at speed c.
• C) The clock runs fast compared to an identical clock at rest in the observer's hand.
• D) The clock appears thicker, front to back, than the identical clock in observer's hand.

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