A circular loop of radius 14 cm carries a current of 16 A. A flat coil of radius 0.68 cm, having 42 turns and a current of 1.4 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?

a

The magnitude of magnetic field is  

b

The torque is  

Explanation:

From the question we are told that

     The radius of the circular loop is

      The current carried by the circular loop is  

       The radius of the flat loop is

       The current carried by the flat loop

The magnitude magnetic field produce at the center  due to the circular loop  is mathematically represented as

Where is the permeability of free space with a value of

Substituting values

The torque on the coil due to the loop is mathematically represented as

Where A is the area and it is evaluated as

N is the number of turns with value N =  42 turns

  No substituting values into the equation for torque

i think the answer is a, hope this : )

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.