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A slender rectangular bar magnet is hung so that it can oscillate freely in a uniform magnetic field, and its time period is T. The magnet is then cut into two identical parts, each having half the original length. If one of these halves is suspended freely in the same field and allowed to oscillate, its time period is T'. What is the value of T'/T?

1. 1/(2√(2))
2. 1/2
3. 2
4. 1/4

Correct answer: 1/2

Solution

When the bar magnet is cut in half, its length is reduced, which affects its moment of inertia. The time period of oscillation is proportional to the square root of the length of the magnet, leading to a new time period that is half of the original.

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