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