Question

The effective length of a magneit is $31.4cm$ and its pole strength is $0.8Am$. The magnetic moment, if it is bent in the form of a semicircle is ________ $A{m}^2$

• A. $1.6$
• B. $1.2$
• C. $0.16$
• D. $0.12$

Answer 1

The correct option is C $0.16$

Length of the magnet $l=31.4cm$
Radius of the semicircle $r=\frac{l}{\pi }=\frac{31.4}{3.14}=10cm=0.1m$
Distance between two poles of magnet $d^{\prime }=2R=0.2m$
Pole strength $m=0.8Am$
Magnetic moment $M=m{d}^{\prime }=0.8\times 0.2=0.16A{m}^2$
Option C is correct.