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In physical theories, a test particle, or test charge, is an idealized model of an object whose physical properties (usually mass, charge, or size) are assumed to be negligible except for the property being studied, which is considered to be insufficient to alter the behaviour of the rest of the system. The concept of a test particle often ...
A recent study used four even-numbered isotopes of ytterbium to test the formula Q w = −0.989 N + 0.071 Z, for weak charge, with N corresponding to the number of neutrons and Z to the number of protons. The formula was found consistent to 0.1% accuracy using the 170 Yb, 172 Yb, 174 Yb, and 176 Yb isotopes of ytterbium. [6]
A proton is a stable subatomic particle, symbol p, H +, or 1 H + with a positive electric charge of +1 e (elementary charge).Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio).
When charged particles move in electric and magnetic fields the following two laws apply: Lorentz force law: = (+),; Newton's second law of motion: = =; where F is the force applied to the ion, m is the mass of the particle, a is the acceleration, Q is the electric charge, E is the electric field, and v × B is the cross product of the ion's velocity and the magnetic flux density.
In the Standard Model, charge is an absolutely conserved quantum number. The proton has a charge of +e, and the electron has a charge of −e. Today, a negative charge is defined as the charge carried by an electron and a positive charge is that carried by a proton.
The charge number equals the electric charge (q, in coulombs) divided by the elementary charge: z = q/e. Atomic numbers (Z) are a special case of charge numbers, referring to the charge number of an atomic nucleus, as opposed to the net charge of an atom or ion. The charge numbers for ions (and also subatomic particles) are written in ...
The nucleon group (protons with Q = +1 and neutrons with Q = 0 ) have an average charge of + + 1 / 2 , so they both have hypercharge Y = 1 (since baryon number B = +1 , and S = C = B′ = T′ = 0). From the Gell-Mann–Nishijima formula we know that proton has isospin I 3 = + + 1 / 2 , while neutron has I 3 = − + 1 / 2 .
The elementary charge, usually denoted by e, is a fundamental physical constant, defined as the electric charge carried by a single proton (+ 1e) or, equivalently, the magnitude of the negative electric charge carried by a single electron, which has charge −1 e.