Question:
A 100 turn rectangular coil ABCD is hung from one arm of a balance. A mass 500 g is added to the other arm to balance the weight of the coil. A current 4.9 A passes through the coil and a constant magnetic field of 0.2 T acting inward is switched on such that only arm CD of length 1 cm lies in the field. How much additional mass ‘m’ must be added to regain the balance?
Solution:
When t = 0, the external magnetic field is off.
Mgl = Wcoil l
0.5 gl = Wcoil l
Wcoil = 0.5 9.8 N
Let m be the mass which is added to regain the balance
When the magnetic field is switched is on,
Mgl + mgl = (ILC)l
m = 1 g
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