question_answer

If an electron is not deflected in passing through a certain region of space, then we can assure that:

A)  there is no electric field

B)  there is no magnetic filed

C)  both the fields may exist

D)  none of the above

Correct Answer: C

Solution :

                 As the electron in passing through a certain region of space will suffer no deflection if either no force acts on it or forces acting on it balance each other. So, apart from absence of any field an electron in passing through a certain region of space in presence of a magnetic field will pass undecflected if either the electron is moving parallel to the filled or the magnetic force acting on it is balanced by some other force, say electric force.