Rutherford's nuclear model of an atom postulates that most of the space in the atom is empty, positive charged protons are concentrated in the nucleus, the size of the nucleus is extremely small compared to the size of an atom, electrons move around the nucleus in circular paths called orbits, and the electrostatic force of attraction between electrons and nucleus is balanced by centrifugal force acting on the electrons
Plank's theory of electromagnetic radiation states that electromagnetic radiations are emitted or absorbed discontinuously in the form of packets of energy called photons or quanta
Black body radiation is emitted by an ideal body that emits and absorbs radiations of all frequencies, and the frequency of emitted radiation depends on temperature
Photoelectric effect is when certain metals emit electrons when exposed to light, and the number of electrons emitted is proportional to the intensity of incident light