What is the longest wavelength in the Balmer series (nf = 2)? Remember the Rydberg constant is 1.097x10-2 nm-1

Determine the wavelength if the electron is excited n=2 for Helium (Z=2).( E=(-13.6ev)Z2/n2 and 1/mu=1/hc(En-En-1)

When an excited hydrogen atom returns to the ground state light of wavelength λ = 102.5 nm is emitted. The Rydberg constant is R = 1.097 x 107 m-1. What was the principle quantum number n of the excited state? Select one: a. 3 b. 2 c. 5 d. 4

Material Si Ge GaAs effective mass parameters: Electron Effective Mass 1.08mo 0.55mo 0.067mo Determine the number of quantum states [er unit volume (3D mate- rial) #/cm³ at T=300K for Si, Ge, and GaAs at an energy of E = kT. What do you observe about the relationship between effective mass and the # of states.