Question

A straight horizontal wire of mass 10 mg and length 1.0 m carries a current of 2.0 A. What minimum magnetic field B should be applied in the region, so that the magnetic force on the wire may balance its weight?

Answer 1

Given:
Mass of the wire, M = 10 mg = 10⁻⁵ Kg
Length of the wire, l = 1.0 m
Electric current flowing through wire, I = 2.0 A
As per the question, the weight of the wire should be balanced by the magnetic force acting on the wire.Also angle between the length of the wire and magnetic field is 90°
Thus, Mg = IlB, where
g is the acceleration due to gravity = 9.8 m/s²
 B is the applied magnetic field
So,
`B = (Mg)/(Il)`
= `(10^-5xx9.8)/(2xx1)`
= 4.9 ×10^-5 T