JEE Main Physics Class 12 Moving Charges and Magnetism Part 2 Questions

In the given figure, The direction of magnetic moment is from South to North. When second magnet is kept in the magnetic field produced by firstmagnet, the torque acting on second magnet is given by
  τ=M2×B1
|τ|=M2B1‌sin‌θ (∴ θ = 90°)
|τ|=M2B1
Point P lie on equitorial position, so
B1=

μ0

4π

M1

r3

|τ|=(

μ0

4π

M1

r3

)M2
M1=M2=1A−m2,r=1m (given)
|τ||=

10−7×1×1

(1)3

⇒|τ|=10−7‌Nm
⇒|τ|=1×10−7‌Nm