What best describes the set of focal points of a thin convex lens?

two focal points on opposite sides of the lens, with one point twice as far from the lens as the other point

two focal points on the same side of the lens, with one point twice as far from the lens as the other point

two focal points on opposite sides of the lens, each the same distance to the lens one focal point located either in front of or behind the lens

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?