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 non - zero) work on each particle .
D. the magnetic forces do equal are necessarily negligible .

Answer

B

Explanation

The magnetic force acting on electron and proton is perpendicular to their motion , hence wrok dne by magnetic force
`W = F s cos 90^(@) = 0 `