Richardson-Dushman Theory Of Thermionic Emission

The figure depicts the excitation of an electron into the conduction band thus leaving a hole in the valence band. An electron-hole pair is called an exciton, and the natural physical separation between them is called the excitonic Bohr radius and is characteristic of each material. Thus when a semiconducting material approaches a size nearing its Bohr excitonic radius, the exciton is said to be confined within the particle and is called quantum

When light is absorbed the electrons get excited and go into a higher energy level, so it move much more freely. This produces an electrical

- I think that the electrons that are emitted from the cathode are emitted with a range of velocities (perhaps like a Boltzmann distribution where average speed clusters in the middle of the range).

A chemical reaction involving the transfer of electrons rather than molecules is classified as a Redox reaction. A reaction involving the loss of electrons is called Oxidation, and a reaction involving the gain of electrons is called Reduction. Oxidation and Reduction always occur together, as one reactant loses electrons, and the other gains them. This exchange often effects the physical states of molecules, as their solubility is changed with their charge.

In paragraph eleven of "Energy Story" it explains how electrons can work. The author states "Electrons can be made to move from one atom to another." and continues to "When

The 1958 Nobel Prize in Physics was awarded to Pavel Alekseyevich Cherenkov, Ilya Frank and Igor Tamm for the discovery and the interpretation of the Cherenkov Effect. Cherenkov radiation is the electromagnetic radiation emitted by particles moving through a medium faster than the speed of light in the same medium. It was fist a detected by Soviet scientist Pavel Alekseyevich Cherenkov, of who the effect is named after and a theory was later developed by Ilya Frank and Igor Tamm. Cherenkov’s contributions still live on as an invaluable tool in today's nuclear and subatomic particle physics with examples that include a way to detect and quantify the characteristics of subatomic particles to analyzing high energy cosmic signals from the deepest regions of space. More down to earth uses consist of safety procedures for nuclear reactors and the detection of low concentration biomolecules in the sick and elderly.

Charges that build up as static electricity on an object do not stay there forever. Electrons like to move, returning to the object to its neutral state. When a negatively charged object and a positively charged object come together, electrons transfer until both objects have an equal charge. The loss of static electricity as electric charges transfer is called static discharge. Normally, a static discharge creates a spark. When electrons transfer between objects they heat the air around the path until it glows, which is the spark we see.

An electric current exists when there is a net flow of charge through a given area. Electrons flow from the negatively charged region to the positively charged region. This is usually accomplished by using an electrical conductor which allows the electrons to pass freely through the material (Serway, et al. 709). This flow of electrons can generate heat when collisions between the molecules and electrons occur. These collisions then cause the molecules to break apart thus releasing heat. Some common examples of electrical energy are lightning, static electricity, and wiring outlets (Coleman, et al. 82). For the wildland firefighter, lightning is probably the

One of J.J. Thomson's most significant contributions to science, and thus to the study of atomic theory, was his discovery of the electron. Before the discovery of the electron, the atom was already associated with having electric charges-both positive and negative-but the idea of an electron existing as its own particle was unheard of. It was in 1897 when Thomson first conducted the beginning of his now famous experiment, in which he used a cathode ray tube to aid in his findings. A cathode ray tube, is a vacuum tube in which cathode rays, negatively charged particles, are produced at the cathode and travel through the vacuum, which is created when gas is extracted from the tube. J.J. Thomson discovered that in order to determine

In thermal escape, particles get heated up by the sun and release this heat by giving off UV radiation which destroys hydrogen particles. Thermal escape happens in two processes, Jeans escape and hydrodynamic

The process of losing electrons is called oxidation and the process of gaining electrons is called reduction. When transferring electrons between two substances, one always reduces and another one oxides known as a redox reaction.

from atoms, generating a flow of electricity.” Knowing this new information, it is possible that

Chemical reactions that release energy are called exothermic reactions, these reactions are observed by an increase in temperature of the reaction mixture.

b) How the Quantum Free Electron Theory predicts that the conductivity of metals decreases as the temperature increases.

The outer shell of electrons that orbit the nucleus of an atom is called the valance shell. This is what makes a copper atom conduct. For a copper atom the number of electrons is one. When a charge of electricity is placed in the end of a wire the electrons move into the wire. Since there is only one electron in the valance shell of a copper atom it can be easily dislodged with a small amount of energy causing it to jump to the next atom. This will then cause the valance electron of that atom to jump to the next atom and so forth. This movement happens very fast making it possible for a large number of electrons to move through the wire. An example of a conductive atom is shown figure 1.