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?

Options

A. `(Mg)/(2 nil)`
B. `(Mg)/(nil)`
C. `(2 Mg)/(nil)`
D. `((Mg)/(nil))^(2)`

Answer

A

Explanation

Deflecting torque `= niAB sin 90^(@) = nil^(2)B`
Restoring torque `= Mg . (l)/(2)`
For tipping `nil^(2) B ge (Mgl)/(2)`
`B ge (Mg)/(2nil)`
`B_(min) = (Mg)/(2nil)`