A star is moving away from Earth and shift in spectral line of wavelength 5700 Å is 1.90 Å . Velocity of the star is

Question

A star is moving away from Earth and shift in spectral line of wavelength 5700 Å is 1.90 Å . Velocity of the star is (A) 50 km s- 1 (B) 70 km s- 1 (C) 85 km s- 1 (D) 100 km s- 1

Tardigrade Admin · Accepted Answer

Δ λ =( upsilon/c) λ ∴ upsilon=(c Δ λ /λ ) Or upsilon=(3 × 108 × 1.9 × 10- 10/5700 × 10- 10)=100 km s- 1

Q. A star is moving away from Earth and shift in spectral line of wavelength $5700 Å$ is $1.90 Å$ . Velocity of the star is

$50 km s^{- 1}$

$70 km s^{- 1}$

$85 km s^{- 1}$

$100 km s^{- 1}$

$Δ λ = \frac{υ}{c} λ$
$∴ υ = \frac{c Δ λ}{λ}$
Or $υ = \frac{3 \times 1 0 ^{8} \times 1.9 \times 1 0 ^{- 10}}{5700 \times 1 0 ^{- 10}} = 100 km s^{- 1}$

Q. A star is moving away from Earth and shift in spectral line of wavelength 5700Å is 1.90Å . Velocity of the star is

50kms−1

70kms−1

85kms−1

100kms−1