Optics Problems - Numerical 28

In a star, hydrogen emits waves of l = 650 nm. The “red-shift” in the wave length is 1.5 nm. What is the speed of the star with respect to Earth?

Sub Topics

Suggested solution:

Since a 'red-shift' is observed, the star is moving away from the Earth.

Let v be the speed of the star.

Obviously,

Given : Dl = 15 A = 15 x 10^-¹⁰m, l = 6.5 x 10^-⁷, c = 3 x 10⁸ms^-¹

= 6.923 x 10⁵ms^-¹