Question

an electron beam moving towards east is deflected north by magnetic field. what is the direction of the magnetic field?

Answer 1

the direction will go in south

Answer 2

Right hand rule:
direction of velocity of positive charge : Index finger
direction of magnetic field : middle finger
direction of force : thumb

1. According to right hand rule, a proton would deflect to south direction. But the charge carried by electron is negative. So it will be deflected towards North.

2.Using right hand rule, the direction of magnetic field would be towards East.