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单词 excitation
释义
excitation

Physics
  • 1. A process in which a nucleus, electron, atom, ion, or molecule acquires energy that raises it to a quantum state (excited state) higher than that of its ground state. The difference between the energy in the ground state and that in the excited state is called the excitation energy. See collective excitation; energy level; quasiparticle.

    2. The process of applying current to the winding of an electromagnet, as in an electric motor.

    3. The process of applying a signal to the base of a transistor or the control electrode of a thermionic valve.


Astronomy
  • A process by which an electron bound to an atom acquires sufficient energy to transfer from a lower energy level to a higher energy level. The atom is then excited. Excitation can occur in two ways. In collisional excitation a particle such as an electron collides with an atom and transfers some of its energy to the atom. If the energy corresponds exactly to the difference between two energy levels, the atom becomes excited. In radiative excitation a photon of radiation is absorbed by an atom. The photon’s energy must exactly equal the difference between the two energy levels. In both cases, when the electrons return to lower energy levels they emit photons.


Chemistry
  • A process in which a nucleus, electron, atom, ion, or molecule acquires energy that raises it to a quantum state (excited state) higher than that of its ground state. The difference between the energy in the ground state and that in the excited state is called the excitation energy. See energy level.


Electronics and Electrical Engineering
  • 1. The addition of energy to an atom or molecule, transferring it from the ground state to a higher energy level.

    2. The application of a signal to the base or control electrode of a transistor or valve.

    3. The application of voltage to an oscillating crystal.

    4. The application of radiofrequency pulses to a tuned circuit.

    5. The application of current to the winding of an electromagnet in order to produce a magnetic flux. The applied current is called the exciting current.


Biology
  • 1. The act or process of stimulating a cell, especially a nerve cell.

    2. The response of a cell that has been stimulated.


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