question_answer

Two similar bar magnets P and Q, each of magnetic moment M, are taken, If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have             [EAMCET (Engg.) 2000]

A)            Equal pole strength           

B)            Magnetic moment \[\frac{M}{4}\]

C)            Magnetic moment \[\frac{M}{2}\]                                 

D)            Magnetic moment M

Correct Answer: C

Solution :

                   If pole strength, magnetic moment and length of each part are  \[{m}',{M}'\]and \[{L}'\]respectively then    \[{m}'=\frac{m}{2}\]                             \[{m}'=m\]    \[{L}'=L\]                              \[{L}'=\frac{L}{2}\]   \[\Rightarrow {M}'=\frac{M}{2}\] \[\Rightarrow {M}'=\frac{M}{2}\]