Question

Two identical bar magnets are fixed with their center at a distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the center O as shown in the figure. The force on the charge Q is:
    

(A) Zero
(B) Directed along OP
(C) Directed along PO
(D) Directed perpendicular to the plane of the paper

Answer 1

Hint : A magnetic field is produced whenever an electrical charge in motion. The spinning and orbiting of the nucleus of an atom produces a magnetic field as does electrical current flowing through a wire. The direction of the spin and orbit determine the direction of the magnetic field. Since the charge is at rest, zero force acts on it.

Complete step by step answer

A Stationary charge Q is placed at P in between the gap of the two magnets at distance D $$ from the center O as shown in the figure.
To find out the force on charge we have two methods:
(1) By concept: since the Q charge particle is in a rest position so it will not produce a magnetic field, so it will not experience any force due to other magnetic fields.
(2) By formula: magnetic force is given by:
                                  $F=q.v.B$
$v$= velocity of the charged particle
$q$ = charge on particle
$B$ = magnetic field
In this case, Velocity of the particles Zero.
$F=q\times 0\times B$
$\therefore F=0$
So, option (A) is correct.

Note
Electric field cannot exist without a magnetic field but we can have a magnetic field without an electric field. Magnetic fields can be produced by moving charge only. Magnetic forces are much stronger than electric forces.