Electric Area of an Extremely Short Pulse and Moment of Force

The electric area of a radiation pulse, which is defined as a time integral of the electric field strength, is interpreted as a mechanical moment of the Lorentz force acting on a unit electric charge upon its interaction with the radiation pulse. Correspondence between the classical mechanics law of conservation of momentum and the change in the moment of force upon the interaction of a quantum object with an intense extremely short radiation pulse is demonstrated. The high efficiency of acceleration of charged particles with quasi-unipolar radiation pulses is confirmed.