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Question
A straight wire of mass 200 g and length 1.5 m carries a current of 2 A. It is suspended in mid air by a uniform magnetic field B. What is the magnitude of the magnetic field?
Solution
Mass of the wire, m = 200 g = 0.2 kg
Length of the wire, l = 1.5 m
Current in the wire, I = 2 A
In the equilibrium position, the net force on the rod will be zero.
Thus,
\[mg = BIl\]
\[ \Rightarrow B = \frac{mg}{Il}\]
\[ \Rightarrow B = \frac{0 . 2 \times 9 . 8}{2 \times 1 . 5}\]
\[ \Rightarrow B = 0 . 65 T\]
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