The Shockley-Ramo theorem is a method for calculating the electric current that a moving charge induces in a nearby electrode. It rests on the idea that the induced current comes from the electrostatic flux lines' own instantaneous change as they end on the electrode, rather than from the rate at which charge physically arrives there, and it expresses that instantaneous current as the product of the charge's value, its velocity, and the component of a fixed weighting electric field in the direction of motion. The theorem appeared in William Shockley's 1938 paper and Simon Ramo's 1939 paper, was later renamed to credit both, and is now applied widely in semiconductor radiation detectors, studies of charge movement in proteins, and the detection of moving ions in mass spectrometry and ion implantation.
Facts
StatementThe instantaneous current i induced on a given electrode by the motion of a charge is i = Ev q v, where q is the charge of the particle, v is its instantaneous velocity, and Ev is the component of the electric field in the direction of v at the charge's instantaneous position, under the conditions that the charge is removed, the given electrode is raised to unit potential, and all other conductors are grounded. 1 Partially Attested
Proof YearShockley's paper appeared in 1938 and Ramo's separate paper in 1939; the earlier year is given. Classification
Statement Form Sources
1. Shockley-Ramo theorem, Wikipedia
Lead section, statement of the theorem
states that the instantaneous current i induced on a given electrode due to the motion of a charge is given by: i=Evqv where q is the charge of the particle; v is its instantaneous velocity; and Ev is the component of the electric field in the direction of v at the charge's instantaneous position, under the following conditions: charge removed, given electrode raised to unit potential, and all other conductors grounded.
Lead section, origin of the theorem
The theorem appeared in William Shockley's 1938 paper titled "Currents to Conductors Induced by a Moving Point Charge" and in Simon Ramo's 1939 paper titled "Currents Induced by Electron Motion".
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