A square coil of edge I having n turns carries a curent i. it is kept on a smooth horizontal plate. A uniform magnetic field B exists in a direction parallel to an edge the total mass of the coil is M. What should be the minimum value of B for which the coil will start tipping over?

Explanation

` Edge = l, Current = I,`
`Turus = n, Mass = m,`
`Magnetic field = B`
`tau = mB sin 90^@ = mB`
Mean torque produced must be able to balance the torqua prodeced due to weight
Now ` tau = tau_(weight)`
`mil^(2) B = (mgl)/(2)`
`B = (mg)/(2 nil)` .