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 horizontal magnetic field B. What is the magnitude of the magnetic field?

Options

A. 2
B. 1.5
C. 0.55
D. 0.65

Answer

d

Explanation

Magnetic force on straight wire ltbRgt `F=Bil sin theta=Bil sin 90^(@) =Bil`
For equilibrium of wire in mid -air
F=mg
Bil =mg
`:. B=(mg)/(il) =(200xx10^(-3)xx9.8)/(2xx1.5) =0.65 T`