What is the purpose of a reference point?

to provide a standard system of measurement

to establish a point from which to measure future distance, or if movement has occurred

to determine the speed of an object in miles per hour

to provide a standard from which to evaluate variables in an experiment

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?