Samantha asked:

“An electron enters a magnetic field at right angles to it. The direction of force acting on the electron will be __________?”

 

Answer: The direction of force is given by Fleming’s Left Hand Rule.

If we stretch the thumb, forefinger and central finger of left hand in such a way that the forefinger shows the direction of magnetic field, the central finger shows the direction of movement of positive charge (or the direction of current) [here the direction must be opposite to the direction of motion of the electron since electron is negatively charged], then the direction of thumb will give the direction of force acting on the charge.