Many impurity atoms in a semiconductor exchange energy and electrons with the electrons in the conduction band. consider the impurity atoms to be in thermal and chemical equilibrium with the conduction band, which can be considered to be both an energy and particle reservoir. assume that a is the ionization energy of the impurity atom. find the probability that an impurity atom is ionized as a function of δ and the chemical potential μ. [hint: consider the electrons with spin "up" or spin "down"]

Aboat that travels with constant speed of 6.10 m/s in still water is to go directly across a river. the current in the river flows at 1.95 m/s. (a) at what angle must the boat be steered?

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

Which of the choices are parts of an atom? select all that apply. a.) compound b.) electron c.) neutron d.) molecule e.) photon f.) proton g.) element