FIGURE 22-8
-A rectangular loop of wire, with dimensions as shown in Figure 22-8, carrying a 2-A current is placed in a magnetic field of 0.8 T. The loop rotates in the magnetic field and at one point makes a 30° angle with the magnetic field. What is the magnitude of the torque acting on the wire?
A) 0.3 Nm
B) 0.4 Nm
C) 0.5 Nm
D) 0.6 Nm
E) 0.7 Nm

Question

FIGURE 22-8 
-A rectangular loop of wire, with dimensions as shown in Figure 22-8, carrying a 2-A current is placed in a magnetic field of 0.8 T. The loop rotates in the magnetic field and at one point makes a 30° angle with the magnetic field. What is the magnitude of the torque acting on the wire?
A) 0.3 Nm 
B) 0.4 Nm 
C) 0.5 Nm 
D) 0.6 Nm 
E) 0.7 Nm

Quizplus · Accepted Answer

The torque on a current-carrying loop in a magnetic field is given by the equation τ = NIAB sin θ, where τ is the torque, N is the number of turns in the loop, I is the current, A is the area of the loop, B is the magnetic field strength, and θ is the angle between the magnetic field and the normal to the loop.

In this problem, N = 1, I = 2 A, A = lw = 0.2 m x 0.4 m = 0.08 m^2, B = 0.8 T, and θ = 30°. Plugging these values into the equation gives:

τ = (1)(2 A)(0.08 m^2)(0.8 T) sin 30°
   = 0.5 Nm

Therefore, the magnitude of the torque acting on the wire is 0.5 Nm, which is answer choice C.

FIGURE 22-8 -A Rectangular Loop of Wire, with Dimensions as Shown in as Shown