Step-by-step explanation:
The region around a moving charge in which it experience a force is called magnetic field. The force is called magnetic force. The force experienced due to moving charge is given by :

q is the charged particle
v is the speed of particle
B is the magnetic field
The number of magnetic field lines passing through any surface is called magnetic flux. The formula used to find the magnetic flux is given by :


Hence, this is the required solution.