Q. 10. Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of magnetic field?
Suppose you are leaning towards the back wall then the electron beam is moving away from your eyes which means the direction of current is towards you (direction of current is taken opposite to the flow of electrons) and the deflection is to the right. Then by Fleming's left-hand rule, the field is in the downward direction.