Two identical bar magnets are fixed with their centres at a distance $d$ apart. A stationary charge $Q$ is…
Two identical bar magnets are fixed with their centres 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 centre $O$ as shown in the figure
The force on the charge $Q$ is
zero
directed along $O P$
directed along $P O$
directed perpendicular to the plane of paper
Solution
The force of attraction on $Q$ by the north pole of first magnet is $F$. The force of attraction on the same charge by $n$ the north pole of another magnet must be opposite to that of the first magnet. Thus, they cancel the effect of one other and hence force on the charge $Q$ is zero.
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The force on the charge $Q$ is