For a specific wavelength 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7 nm. The value of v is :

Question

For a specific wavelength 670 nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7 nm. The value of v is : (A) 3 × 108 ms -1 (B) 3 × 1010 ms -1 (C) 3.13 × 105 ms -1 (D) 4.48 × 105 ms -1

Tardigrade Admin · Accepted Answer

λ text emitted =670 nm λ text obs =670.7 nm v =? c =3 × 108 m / s If v << c (λ text obs -λ text emited /λ text emitted )=( v / c ) (670.7-670/670)=( v / c ) V =3.13 × 105 m / s

Q. For a specific wavelength $670 nm$ of light coming from a galaxy moving with velocity $v$ , the observed wavelength is $670.7 nm$ . The value of $v$ is :

$3 \times 1 0^{8} m s^{- 1}$

$3 \times 1 0^{10} m s^{- 1}$

$3.13 \times 1 0^{5} m s^{- 1}$

$4.48 \times 1 0^{5} m s^{- 1}$

$λ_{emitted} = 670 nm$
$λ_{obs} = 670.7 nm$
$v = ?$
$c = 3 \times 1 0^{8} m / s$
If $v << c$
$\frac{λ _{obs} - λ _{emited}}{λ _{emitted}} = \frac{v}{c}$
$\frac{670.7 - 670}{670} = \frac{v}{c}$
$V = 3.13 \times 1 0^{5} m / s$

Q. For a specific wavelength 670nm of light coming from a galaxy moving with velocity v, the observed wavelength is 670.7nm. The value of v is :

3×108ms−1

3×1010ms−1

3.13×105ms−1

4.48×105ms−1