Question

At rst hydrogen has a spectral line at 165 nm. If the line is observed at 170 nm for the star Proxima, how fast is Proxima moving in km/s

Answer 1

9090.90 Km/s

Step-by-step explanation:

Given:

hydrogen has a spectral line at = 165 nm

Line is observed at = 170 nm

Now, from the Hubble's law

`v=(\Delta\lambda)/(\lambda)*\ C`

Where,

v is the velocity

Δλ = Change in wavelength = 170 - 165 = 5 nm

λ = Actual wavelength

C is the speed of the light

on substituting the respective values, we get

`v=(5)/(165)*3times10^8`

or

v = 90.90909 × 10⁵ m/s

or

v = 9090.90 Km/s