Suppose a ringing bell is placed inside a sealed jar filled with air. The air is then removed from the jar, creating a vacuum. Described the difference in what a person nearby hears before and after the air is removed from the jar.

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?