A distant source of light is emitting one of the Balmer lines at 656 nm. The light is observed to be at a wavelength of 680 nm due to a motion of the source. The velocity of the source is

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Quizplus · Accepted Answer

The observed increase in wavelength (from 656 nm to 680 nm) indicates a redshift, which means the source is moving away from the observer. The velocity can be calculated using the formula for redshift: $z = \frac{\Delta \lambda}{\lambda_{\text{original}}} = \frac{680 - 656}{656} = \frac{24}{656}$. The velocity $v$ is related to the redshift $z$ by $v = zc$, where $c$ is the speed of light. Substituting the values, we get $v \approx 0.036c$, indicating the source is moving away at 3.6% the speed of light.

A Distant Source of Light Is Emitting One of the Balmer