Physics-
General
Easy
Question
A small coil C with N = 200 turns is mounted on one end of a balance beam and introduced between the poles of an electromagnet as shown in figure. The cross sectional area of coil is A= 1.0 cm2, length of arm OA of the balance beam is 
When there is no current in the coil the balance is in equilibrium. On passing a current I = 22 mA through the coil the equilibrium is restored by putting the additional counter weight of mass 
on the balance pan. Find the magnetic induction at the spot where coil is located.
- 0.4 T
- 0.3 T
- 0.2 T
- 0.1 T
The correct answer is: 0.4 T
On passing current through the coil, it acts as a magnetic dipole. Torque acting on magnetic dipole is counter balanced by the moment of additional weight about position O. Torque acting on a magnetic dipole
.
Again 
= 0.4 T
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