An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because,

Options

A. The two magnetic forces are equal and opposite, so they produce no net effect
B. The magnetic forces do not work on each particle
C. The magnetic forces do equal and opposite (but nonzero) work on each particle
D. The magnetic forces are necessarily negligible

Answer

B

Explanation

When electron and proton are moving under influence of their mutual forces, the magnetic forces will be perpendicular to their motion hence no work is done by these forces.