If an electron and a proton having same momenta enter perpendicular to a magnetic field, then
- they will move undeflected
- curved path of electron and proton will be same (ignoring the sense of revolution)
- path of proton is more curved
- curved path of electron is more curved than that of the proton
Radius of a circular path in a magnetic field depends on the momentum and in this question both have same momentum.
Therefore, they would have same curved path.
The correct option is B.