A rectangular coil consists of N = 160 closely wrapped turns and has dimensions
ID: 1446760 • Letter: A
Question
A rectangular coil consists of N = 160 closely wrapped turns and has dimensions a = 0.400 m and b = 0.300 m. The coil is hinged along the y axis, and its plane makes an angle theta = 30.0 degree with the x axis (see figure below). What is the magnitude of the torque exerted on the coil by a uniform magnetic field B = 0.440 T directed in the positive x direction when the current is I = 1.20 A in the direction shown? If you are looking downward from the positive y direction, what is the expected direction of rotation of the coil? clockwise counterclockwiseExplanation / Answer
The torque is the cross product of magnetic moment and the magnetic field.
The magnetic moment = NIA = 160*1.2*(0.4*0.3) = 23.04 A m^2
The direction is perpendicular to the loop
The magnetic field B = 0.44 T and the angle between magnetic field and magnetic moment = 60 degree
Hence the magnitude = 23.04*0.44*sin(60 deg) = 8.78 Nm.
Direction: clockwise