A positively charged particle (alpha particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is:

(a) towards south

(b) towards east

(c) downward

(d) upward

Which of the following property/properties of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer):

(a) mass

(b) speed

(c) velocity

(d) momentum

A small aluminium rod AB is suspended horizontally from a stand by the ends of two connecting wires as shown in the Figure given here. A horseshoe magnet is placed in such a way that north pole of the magnet is vertically below and its south pole vertically above the aluminium rod. The aluminium rod is connected in series with a battery, a key and a rheostat. How do you think the displacement of rod AB will be affected if:

(i) current in rod AB is increased?

(ii) a stronger horseshoe magnet is used?

(iii) length of the rod AB is increased?

State Flemings left-hand rule.

What is the principle of an electric motor?