CGPET 2015 Solved Paper

Time period of a suspended magnet is given by
T=2π√

I

MB

where, I = momentum of inertia of the magnet about the point of suspension.
M = magnetic moment
B = magnetic field
When the magnet is broken in length
T2′=2π√

I′

M′B

⇒

T

T2′

=√

I

I′

×√

M′

M

= √

mL2

m′L′2

×√

L′

L

Here, and 'are the masses of the magnet and 's are their lengths.= √

m

m′

×√

L

L

′
= √

m

m∕2

×√

L

L∕2

= √2×√2=2 ⇒ T′=

T

2

=

4

2

=2s