Albert Einstein

“ Quanta of energy penetrate the surface layer of the solid, and their energy is transformed, at least partially, in kinetic energy of electrons. The simplest picture is one where the light quantum gives its entire energy to a single electron; we assume that this will occur. However, it must not be excluded that electrons accept the energy of light quanta only partially. An electron that has been loaded with kinetic energy will have lost some of its energy when it arrives at the surface. ”

“ Because of the time averages of the kinetic and potential energy, the energy is 2⁄3 as large as the kinetic energy of a single free gas molecule. Even if something (such as radiative processes) causes the time-averaged energy of a resonator to deviate from the value , collisions with the free electrons and gas molecules will return its average energy to by absorbing or releasing energy. Hence, in this situation, dynamic equilibrium can only exist when every resonator has an average energy . ”

“ Ionization of Gases by Ultraviolet Light We have to assume that in ionization of a gas by ultraviolet light always one absorbed light energy quantum is used for the ionization of just one gas molecule. Firstly it follows that the ionization energy (that is, the theoretically necessary energy to ionize) of a molecule cannot be larger than the energy of an absorbed light energy quantum. ”

“ Denoting the entropy at a particular starting state as S0, and the relative probability of a state with entropy S as W we have in general:
We now consider the following special case. Let a number (n) of movable points (for example molecules) be present in a volume v0, these points will be the subject of our considerations. Other than these, arbitrarily many other movable points can be present. As to the law that describes how the considered points move around in the space the only assumption is that no part of the space (and no direction) is favored over others. ”

“ If the formula derived is correct, then Π, as a function of frequency of the excited light represented in Cartesian coordinates, must be a straight line, whose inclination is independent from the nature of the substance investigated. ”

“ Lenard PE is always significantly larger than Rβν, as the voltage that the cathode rays have had to traverse to generate even visible light is in some cases several hundred, in other cases thousands of volts. ”

“ We expand the Z-component of the electric force (Z) in a given point in the space between the time coordinates of t=0 and t=T (where T is a large amount of time compared to all the vibration periods considered) in a Fourier series where and . Performing this expansion arbitrarily often with arbitrarily chosen initial times yields a range of different combinations for the quantities Aν and αν. ”