In the circuit represented by the figure below the bulb B ha

In the circuit represented by the figure below the bulb B has a higher resistance than the two outside bulbs. The object shown below which has two blocks of plastic (the one on the left with a large negative charge and the one on the right with an equally large positive charge) connected by a block of wood is going to be placed instantaneously in the gap at the top of the circuit above. This object will not touch the wire on either side of the gap. Would the charges in the segment of the wire to the right of the gap experience any electric force when the block is in place? If yes, what would the direction of that force be? If no, why not? Would you expect any charges in the electric circuit to move? If yes, how? If no, why not? If you think charges in the circuit will move which ones will move and where?

Solution

Ans

The conducting wire in the given circuit has excess electrons.These electrons distribute themselves

in a way that the mutual repulsive force between two electrons is minimum. Now when the block of

charge is placed between the gap, the positive part of the block will induce the electrons in the segment

of the wire to the right of the gap.

As the electric field due to positive chagein the block is +ve i.e in nature, this force will also push away

the positive charges from the block to c and attract the electrons towards it.

When the block of charges ( separated by non-conducting wood) is placed inside the wire,

the negative part will induce repulsion on the wire connected with the left segment where as

the postive charge will induce the other segment.The forces will make the free electrons move.

Electrons will be repelled from the negative chrage and will be attracted towards the positive charge.

But this movement will be internal. As the block has net charge zero and the conductor is

also neutral, the net force will also be zero.