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Moving Charges and Magnetism — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsMoving Charges and Magnetism3 Marks
Question
A rectangular wire loop of width a is suspended from the insulated pan of a spring balance, as shown in A current i exists in the anti-clockwise direction in the loop. A magnetic field Bexists in the lower region. Find the change in the tension of the spring if the current in the loop is reversed.
✓

Answer


Current anticlockwise
Since the horizontal Forces have no effect.
Let us check the forces for current along AD & BC [Since there is no $\overrightarrow{\text{B}}$ ]
In AD, F = 0
For BC
F = iaB upward
Current clockwise
Similarly, F = - iaB downwards
Hence change in force = change in tension
= iaB - (-iaB) = 2 iaB

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