The hydrogen Balmer line Hb has a wavelength of 486.1 nanometres in the laboratory.The same line is observed in a quasar at 2430.5 nm.What is the change in wavelength (in nm)for the line in this quasar spectrum?

Question

Quizplus · Accepted Answer

Using the Doppler effect equation, we can calculate the change in wavelength:
∆λ/λ = v/c
where ∆λ is the change in wavelength, λ is the rest wavelength (486.1 nm), v is the velocity, and c is the speed of light.
Rearranging the equation, we get:
∆λ = λ(v/c)
Substituting the given values, we get:
∆λ = 486.1 nm((2430.5 nm/486.1 nm) - 1) = 1944.4 nm - 486.1 nm = 1458.3 nm or 1.4583 μm
Therefore, the change in wavelength is 1944.4 nm (option C).

The Hydrogen Balmer Line Hb Has a Wavelength of 486