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?

Answer 1

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,

\[mg = BIl\]

\[ \Rightarrow B = \frac{mg}{Il}\]

\[ \Rightarrow B = \frac{0 . 2 \times 9 . 8}{2 \times 1 . 5}\]

\[ \Rightarrow B = 0 . 65 T\]