Question

In the spectrum of a galaxy that is travelling away from Earth a hydrogen line is observed to be shifted from 394 nm to 450 nm. Calculate the velocity of recession of the galaxy.

Answer 1

The velocity of recession of the galaxy will be 37.3×10⁶ m/sec. The concept of Doppler effect is employed in the given problem.

What is the Doppler effect?

A sudden change in the frequency due to the distance between the objects and source is explained by the Doppler effect.

As the source and observer travel toward each other, the frequency of sound, light, or other waves increases or decreases.

A passing siren's rapid change in pitch, as well as astronomers' redshift, are both caused by this phenomenon.

Applications of the Doppler effect;

The rest wavelength is,$\rm \lambda_0 = 394 \ nm$

The distant wavelength is,$\rm \lambda = 450 \ nm$

The velocity of recession  is,V

The recession velocity is found as;

$\rm V = (1-\frac{\lambda}{\lambda_0} )C \\\\ \rm V = (1-\frac{394}{450} )\times 3 \times 10^8 \\\\ V = (1- 0.875)\times 3 \times 10^8 \\\\ V = 37.3 \times 10^6 \ m/sec$

Hence, the velocity of recession of the galaxy will be 37.3×10⁶ m/sec.

To learn more about the Doppler effect, refer to the link;

brainly.com/question/15318474

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