# electromagnetic momentum

## electromagnetic momentum

[i¦lek·trō·mag′ned·ik mə′men·təm]
(electromagnetism)
The momentum transported by electromagnetic radiation; its volume density equals the Poynting vector divided by the square of the speed of light.
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References in periodicals archive ?
Electromagnetic Momentum. American Journal of Physics, 2012, v.
For the rewound six-phase cage motor loaded by the rated load, the phase current decreased by 16,4 %, power required from the network decreased by 4,4 %, power losses decreased by 13,5 %, power factor increased by 4,7 %, efficiency factor increased by 3,8 %, and electromagnetic momentum remained almost unchanged, compared to the same parameters of three-phase motor.
Defining the corresponding electromagnetic momentum density as the vector product of fields [mathematical expression not reproducible] [15], and taking into account Equation (5), we obtain:
Equation (11) enables us to identify the evolution direction of electromagnetic momentum density ([??] x [??]) with the normal to the wave front ([nabla]S).
This position prevents an analysis of processes connected with transformation of the electromagnetic momentum into mechanical one and vice versa at propagation of light in an inhomogeneous optical medium and prevents using a powerful method of a calculation a magnitude of optically induced forces (OIF) by means of an analysis of a change of the momentums.
Thus, OIF is responsible for a change of the mechanical momentum and COIF is responsible for a change of the electromagnetic momentum. Usually, relations between electromagnetic and mechanical MDFs before interaction are known.
The electromagnetic momentum can be expressed as the multiplication of the vector (H) by the velocity (v), as (H x v).
In (3)-(5), (c) is the velocity of light, ([rho]) is the volume-density charge of a mass, and the vector (v) is the velocity of the electromagnetic momentum where v = ([v.sub.x'], [v.sub.y'], [v.sub.z']).
while the electromagnetic momentum density [[??].sub.e.m.] is the second term on right-hand side of the same equation (2).
This is made in terms of the electromagnetic momentum density
can be interpreted as a local electromagnetic momentum density of the radiation field, with [??] standing for the Poynting vector.
can be interpreted as an electromagnetic momentum density with S denoting the Poynting vector, and

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