Question

By removing the inducing magnet, the induced magnetism is
$\left( A \right)$ Finished after some time.
$\left( B \right)$ Finished just after.
$\left( C \right)$ Not finished for a long time.
$\left( D \right)$ Not changed.

Answer 1

Hint – The concept used in this question is that when a permanent magnet is brought close to a magnetic object such as iron without touching it, the iron rod behaves like a magnet and attracts iron materials such as pins, clips etc. Once the magnet is withdrawn, the iron loses its magnetic strength and the materials attracted to the iron fall down. So using this magnet property to get to the question's answer.

Complete step-by-step answer:
Induced magnetism
The magnetic substance acquires magnetism when it is placed close to the magnet called induced magnetism.
Characteristics of induced magnetism:
$\left( 1 \right)$ There is no separate life for the induced magnetism.
$\left( 2 \right)$ Magnetic induction is temporary.
$\left( 3 \right)$ Induced magnetism takes priority over attraction.
Consider the case when we rub a magnet on a long iron pin it develops induced magnetism in it (so the magnet behave as a inducer magnet for the iron pin) half of iron pin stick to magnet and half of iron pin stands still outside the magnet, now when we brought another iron pin close to the part of the pin which is outside the magnet, it will feel a force of attraction this is because of induced magnetism and when we remove the magnet induced magnetism is lost and the iron pin did not feel any force of attraction so by removing the inducing magnet the induced magnetism finished just after.
So this is the required answer.
Hence option (B) is the correct answer.

Note – A fascinating fact about induced magnetism is that if we take an iron rod and find the inducer magnet's North Pole, then the end of the rod near the North Pole becomes a south pole and the North Pole becomes the far end of the rod. The magnetic pole causes a near-end opposite polarity and equal polarity on the farther end of the iron line.