Question

A circular loop of radius 14 cm carries a current of 15 A. A flat coil of radius 1.2 cm, having 65 turns and a current of 1.1 A, is concentric with the loop. The plane of the loop is perpendicular to the plane of the coil. Assume the loop's magnetic field is uniform across the coil. What is the magnitude of (a) the magnetic field produced by the loop at its center and (b) the torque on the coil due to the loop?

Answer 1

Solution-

Using formula:

B= u0I1/2R1

=(4*3.14*10^-7)*(15)/(2*0.14)

= 0.0000672

= 6.72*10^5  B

b) Using the formula  
                              τ = BIAN
                                 = BI(πr^2)N
putting the values in the above equation
         I = 1.1 A
         π = 3.14
         r = 1.2*10^-2m
        N = 65 turns

= (6.72*10^5*1.1)*(3.14*(1.2*10^-2)^2)(65)

= 21725.38