Question

an electron does not sufferany deflection while passing through a region of uniform magnetic field.what is the direction of the magnetic field?

Answer 1

we know ,
F=q (V x B)
where F is the magnetic force act on particle , q is charge of particle , V is the velocity of particle and B is the magnetic field .
if V parellel to B
then F=0
it means when when direction of moving particle is parellel to direction of magnetic field , particle doesn't deflect in its direction .
according to above question ,
electron doesn't suffering deflection when passong through a region of magnetic field .hence magnetic field must be the direction of electron .