Question

The magnetic potential at a point on the axial line of a bar magnet of dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment $\frac { M } { 4 }$ at the same point

• A.
• B.
• C. $\frac { V } { 2 }$
• D. $\frac { V } { 4 }$

Answer 1

Answer: (D)

$\frac { V } { 4 }$

Answer 2

Magnetic potential at a distance d from the bar magnet on it's axial line is given by

$V = \frac { \mu _ { 0 } } { 4 \pi } \cdot \frac { M } { d ^ { 2 } }$ ⇒ $V \propto M$ ⇒ $\frac { V _ { 1 } } { V _ { 2 } } = \frac { M _ { 1 } } { M _ { 2 } }$

⇒ $\frac { V } { V _ { 2 } } = \frac { M } { M / 4 }$ ⇒ $V _ { 2 } = \frac { V } { 4 }$