You see a galaxy in which the H$\alpha$ line (rest wavelength = 656.3 nm) is observed at a wavelength of 756.3 nm.What would be the observed wavelength of a particular helium line that has a rest wavelength of 1,083 nm?
A) 1,083 nm
B) 1,183 nm
C) 1,248 nm
D) 1,440 nm
E) 3,142 nm

Question

Quizplus · Accepted Answer

The observed wavelength is given by the formula:observed wavelength = rest wavelength * (1 + z)where z is the redshift.The redshift is given by the formula:z = (observed wavelength - rest wavelength) / rest wavelengthIn this case, the observed wavelength is 756.3 nm and the rest wavelength is 656.3 nm.So, the redshift is:z = (756.3 nm - 656.3 nm) / 656.3 nm = 0.15Now, we can use the formula for the observed wavelength to find the observed wavelength of the helium line:observed wavelength = 1,083 nm * (1 + 0.15) = 1,248 nmSo, the correct answer is C.

You See a Galaxy in Which the H α\alphaα Line (Rest Wavelength = 656

You See a Galaxy in Which the H $\alpha$ Line (Rest Wavelength = 656