Optics Question 243

Question: A star emits light of $ 5500{AA} $ wavelength. Its appears blue to an observer on the earth, it means

[DPMT 2002]

Options:

A) Star is going away from the earth

B) Star is stationary

C) Star is coming towards earth

D) None of the above

Show Answer

Answer:

Correct Answer: C

Solution:

Blue radiations have the wavelength around 4600 $ \overset{o}{\mathop{A}} $ . It shows that apparent wavelength is smaller than the real wavelength. It means that the star is proceeding towards earth.



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