A rectangular loop of wire has dimensions 0.505 m by 0.285 m. The loop is pivote
ID: 1262064 • Letter: A
Question
A rectangular loop of wire has dimensions 0.505 m by 0.285 m. The loop is pivoted at the x axis and lies in the xy plane as shown in the figure below. A uniform magnetic field of magnitude 1.35 T is directed at an angle of 40.0
A rectangular loop of wire has dimensions 0.505 m by 0.285 m. The loop is pivoted at the x axis and lies in the xy plane as shown in the figure below. A uniform magnetic field of magnitude 1.35 T is directed at an angle of 40.0° with respect to the y axis with field lines parallel to the yz plane. The loop carries a current of 0.891 A in the direction shown. (Ignore gravitation.) We wish to evaluate the torque on the current loop. a- Compute the magnitude of the magnetic moment of the loop. (b) What is the angle between the magnetic moment vector and the magnetic field? (c) Compute the torque on the loop using the results to parts (k) and (l).Explanation / Answer
a)
Magnetic moment is given by :
M = I*A
where A = area of loop = 0.505*0.285 = 0.144m2
I =current = 0.891 A
So, M = 0.891*0.144 = 0.128 A.m2<----------answer
b)
Mt right hand thumb rule we get the direction of Magnetic moment to be in -ve z axis
So, angle between moment vector and field = 90+40 = 130 degrees <--------answer
c)
Torque,T = M*B*sinQ
where Q =angle between moment vector and field = 130 degrees
B = 1.35 T
So, T = 1.25*0.128*sin(130 degrees) = 0.123 N.m <-------answer