Due to Doppler's effect, the shift in wavelength observed is `0.1 Å` for a star producing wavelength 6000 Å. Velocity of recession of the star will be

Options

A. 2.5 km/s
B. 10 km/s
C. 5 km/s
D. 20 km/s

Answer

C

Explanation

`Delta lambda = 0.1 A^(@), lambda = 6000 A^(@), c = 3 xx 10^(8) m//s, v = ?`
`(Delta lambda)/(lambda) = (v)/(lambda)`
`v = (Delta lambda xx c)/(lambda)`
`v = (0.1 xx 3 xx 10^(8))/(6000) = (3 xx 10^(7))/(6 xx 10^(3)) = (1)/(2) xx 10^(4)`
`v = 0.5 xx 10^(4) = 5 xx 10^(3)m//s = 5 km//s`