question_answer

Two short magnets of magnetic moment \[\,1000\text{ }A{{m}^{2}}\] are placed as shown at the comers of a square of side 10 cm. The net magnetic induction at P is

A) 0.1 T                

B) 0.2 T

C) 0.3 T                

D) 0.4 T

Correct Answer: A

Solution :

Point P lies on equatorial line of magnet and axial line of magnet as shown \[{{B}_{1}}=\frac{{{\mu }_{0}}}{4\pi }\cdot \frac{M}{{{d}^{3}}}\,=\,\,{{10}^{-7}}\,\times \,\,\frac{1000}{{{(0.1)}^{3}}}\,\,=\,\,0.1\,T\] \[{{B}_{2}}=\frac{{{\mu }_{0}}}{4\pi }\cdot \frac{2M}{{{d}^{3}}}\,\,=\,{{10}^{-7}}\,\times \,\,\frac{2\times 1000}{{{(0.1)}^{3}}}\,\,=\,\,0.2\,T\] \[\therefore \,\,\,\,{{B}_{net}}={{B}_{2}}-{{B}_{1}}=0.1\,T\]