In this lesson, we will learn how to determine the change in the apparent wavelength of light waves emitted from a moving source.

Q1:

An astronomer estimates the velocity of a comet to be 1,600 km/s away from his position. The shortest wavelength of light visible to the astronomer is 400 nm. What would the shortest wavelength of light emitted from the comet that would be visible to the astronomer be? Answer to the nearest nanometer. Use a value of 3×10 m/s for the speed of light.

Q2:

The change in the apparent wavelength of light due to the motion of an object, Δ𝜆, depends on the wavelength of the light measured by an observer at rest relative to the emitting object, 𝜆; on the velocity of the object relative to the observer, 𝑣; and on the speed of light, 𝑐. Which of the following formulas correctly relates these quantities?

Q3:

Light from an object has an apparent wavelength of 540 nm. The magnitude of the change in the wavelength due to the motion of the object relative to an observer is 12 nm.

What is the maximum possible value of the wavelength of the light emitted by the object?

What is the minimum possible value of the wavelength of the light emitted by the object?

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