Question

What wavelength ? should the astrophysicist look for to detect a transition of an electron from the n=7 to the n=3 level?

Answer 1

using the Debroglies equation,energy can be found,as 1.9773*10*-9
then, energy* wave length= hc
c is the speed of light and is the planks constant.
wave length =1.006*10*-16 m