CGPET 2019 Solved Paper

Given, Length of magnetic needle =2l
Magnetic moment =M
pole strength =mMagnetic moment, M=m×2l ...(i)
According to the question, when magnetic needle is broken into two pieces at the middle as shown in the figure. M′=m×l
M′=m×2l×

1

2

From Eq. (i), we get
M′=

M

2

Pole strength of magnetic needle cannot be changed.
Hence, the correct option is (c), i.e. (

M

2

,m)