The Hδ line has a wavelength of 410.2 nm when observed in the laboratory. If the Hδ 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)$6.0 × 10^7$ m/s away from the observer
D)$6.0 × 10^7$ m/s toward the observer
E)The radial velocity of the star cannot be determined from this information.

Question

Quizplus · Accepted Answer

The difference in wavelength between the laboratory wavelength and the observed wavelength is given as:

Δλ/λ = v/c

where Δλ is the difference in wavelength, λ is the laboratory wavelength, v is the radial velocity of the star, and c is the speed of light.

Substituting the given values, we get:

(410.2 - 410.0)/410.2 = v/c

Solving for v, we get:

v = (0.2/410.2) * c = 146 km/s toward the observer.

Therefore, the correct answer is B.

The Hδ Line Has a Wavelength of 410 6.0×1076.0 × 10^76.0×107

The Hδ Line Has a Wavelength of 410 $6.0 × 10^7$