The light from a distant star is that has a peak in its intensity spectrum at 620 nm and is moving at a rate of 0.024c towards Earth.What is the wavelength of the peak of its intensity spectrum,as observed on Earth?
A) 605 nm
B) 591 nm
C) 650 nm
D) 635 nm

Question

Quizplus · Accepted Answer

The correct answer is A.The wavelength of the peak of the intensity spectrum of the star as observed on Earth is given by:$$\lambda_{obs} = \lambda_{rest} / (1 - v/c)$$where:$$\lambda_{obs}$$ is the observed wavelength$$\lambda_{rest}$$ is the rest wavelengthv is the velocity of the starc is the speed of lightSubstituting the given values into the equation, we get:$$\lambda_{obs} = 620 nm / (1 - 0.024) = 605 nm$$

The Light from a Distant Star Is That Has a Peak