Question

You record the spectrum of a star and find that a calcium absorption line has an observed wavelength of 394.0 nm. This calcium absorption line has a rest wavelength of 393.3 nm. What is the approximate radial velocity of this star?

Answer 1

Answer:

radial velocity = 0.533 × $10^{6}$ m/s

Explanation:

given data

observed wavelength = 394.0 nm

rest wavelength = 393.3 nm

solution

we get here radial velocity  by the Doppler effect of light that is

$\frac{\triangle \lambda }{\lambda} = \frac{v}{c}$     ......................1

v = $\frac{c \times \triangle \lambda }{\lambda}$    

put here value

v = \frac{c \times (\lambda ' - \lambda  }{\lambda}

v = \frac{3 \times 10^8  \times (394 - 393.3}{393.3}

v = 533943.55

v = 0.533 × $10^{6}$ m/s