A rectangular loop carrying current lies in the plane of a uniform magnetic fiel
ID: 1768169 • Letter: A
Question
A rectangular loop carrying current lies in the plane of a uniform magnetic field of magnitude 0.040 T. The loop consists of a single turn of flexible conducting wire that is wrapped around a flexible mount such that the dimensions of the rectangle can be changed. (The total length of the wire is not changed.) As edge length x is varied from appsoximately zero to its maximum value of approximately 4.0 cm, the magnitude of the torque on the loop changes. The maximum value of the torque is 4.8 x 10 ^ -8 Nm. What is the current in the loop when the torque is at its maximum value?
Explanation / Answer
torque on loop is given By T = NIAB sin theta
where I = cuurnet
A = area
N = no. of tunrs
B = magnetic field
theta = 90
here Length L (2* (a+b) = 0.04m
a+b = 0.02 m
area of square = 0.02*0.02 = 4*10^-4
so rearaniugnthe terms
I = T/(NABsin theta)
I = 4.8*10^-8/( 1* 0.04*4*10^-4* 0.04)
I = 75 mA