The H_$\delta$ line has a wavelength of 410.2 nm when observed in the laboratory. If the H_$\delta$ line appears in a stars spectrum at 410.0 nm, what is the radial velocity of the star? A) 146 km/s away from the observer B) 146 km/s toward the observer C) 6.0*10⁷ m/s away from the observer D) 6.0*10⁷ m/s toward the observer E) The radial velocity of the star cannot be determined from this information.

Question

Quizplus · Accepted Answer

The observed wavelength of the line in the star's spectrum is shorter than the laboratory wavelength, which indicates that the star is moving toward the observer. Using the formula for radial velocity, $v_r = c\cdot\Delta\lambda/\lambda$, where $c$ is the speed of light and $\Delta\lambda$ is the difference between the observed and laboratory wavelengths, we can calculate the radial velocity. Plugging in the given values, we get $v_r = c\cdot(410.2	ext{ nm} - 410.0	ext{ nm})/410.2	ext{ nm} \approx 146	ext{ km/s}$. The positive sign indicates that the star is moving toward the observer. Therefore, the correct answer is B.

The H δ\deltaδ Line Has a Wavelength of 410 δ\deltaδ Line Appears in a Stars Spectrum at 410

The H_$\delta$ Line Has a Wavelength of 410 $\delta$ Line Appears in a Stars Spectrum at 410