A square loop (L = 0.20 m)consists of 50 closely wrapped turns,each carrying a current of 0.50 A.The loop is oriented as shown in a uniform magnetic field of 0.40 T directed in the positive y direction.What is the magnitude of the torque on the loop?
A)0.21 N ⋅ m
B)0.20 N ⋅ m
C)0.35 N ⋅ m
D)0.12 N ⋅ m
E)1.73 N ⋅ m

Question

A square loop (L = 0.20 m)consists of 50 closely wrapped turns,each carrying a current of 0.50 A.The loop is oriented as shown in a uniform magnetic field of 0.40 T directed in the positive y direction.What is the magnitude of the torque on the loop? 
A)0.21 N ⋅ m 
B)0.20 N ⋅ m 
C)0.35 N ⋅ m 
D)0.12 N ⋅ m 
E)1.73 N ⋅ m

Quizplus · Accepted Answer

The torque on a current loop in a magnetic field is given by:
τ = NIAxB
where N is the number of turns, I is the current, A is the area of the loop, and B is the magnetic field. In this case, N = 50, I = 0.50 A, A = L^2 = (0.20 m)^2 = 0.04 m^2, and B = 0.40 T.

The direction of the torque is perpendicular to the plane of the loop and the direction of the magnetic field, according to the right-hand rule.

Plugging in the values, we get:
τ = (50)(0.50 A)(0.04 m^2)(0.40 T)sin(90°) = 0.35 N ⋅ m

Therefore, the correct answer is C.

A Square Loop (L = 0