A straight conducting rod of length l and mass is suspended in a horizontal plane by a pair of flexible strings in a magnetic field of magnitude B. To remove the tension in the supporting strings, the magnitude of current in the wire is :
To remove the tension in the supporting strings, the magnetic force (BIl) should balance the gravitational force (mg). Therefore, equating BIl = mg, the current required is I = mg/Bl. Hence, the Correct answer is (c) mg/lB.
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To remove tension in the strings, the magnetic force must balance the gravitational force:
Bil = mg
Rearranging for current I:
I = mg/BL
Thus, the magnitude of current needed to make the net force zero is:
I = mg/BL
Answer: (C) mg/IB
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