Refraction of sound waves often takes place when:
a. there are temperature differences in air
b. there are walls around a room to bounce back sound
c. sound wave frequencies are increased
d. complete sound waves slow down

The nuclear potential that binds protons and neutrons in the nucleus of an atom is often approximated by a square well. imagine a proton conned in an innite square well of length 105 nm, a typical nuclear diameter. calculate the wavelength and energy associated with the photon that is emitted when the proton undergoes a transition from the rst excited state (n 2) to the ground state (n 1). in what region of the electromagnetic spectrum does this wavelength belong?