Three similar magnetic south poles, each of strength 10 Am are placed at the corners of an equilateral triangle of side 20 cm. The magnetic force on one of the pole is:
Magnetic strength of poles,
F12=Repulsive force on the pole 2 due to pole 1,
F32=Repulsive force on the pole 2 due to pole 3,
Net force on the pole 2 is,
As, F=μ04πm1m2r2=10−7×10×100.2×0.2=0.25×10−3 N
Hence, option (D) is the correct answer.