# An electricity and magnetism problem by Prashant Kr

**Electricity and Magnetism**Level 4

A neutral atom of atomic mass number 100 which is stationary at the origin in gravity free space emits an alpha particle (A) in Z- direction. The product ion is P . A uniform magnetic field exists in the X-direction. Disregard the electro magnetic interaction between A and P . If the angle of rotation of A after which A and P meets for the first time is \(\frac{n\pi}{25}\) radians, then what is the value of n?