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CBSE Class 12-science Answered

A rectangular coil of sides l and b carrying a current I is subjected to a uniform magnetic field B acting perpendicular to its plane. obtain the expression for the torque acting on it
Asked by Rajeev | 21 Feb, 2016, 11:49: PM
answered-by-expert Expert Answer
The area of cross-section of the coil is A = lb
 
Now, the magnetic moment of the coil is
 
m = IA = Ilb
 
Now, we know that the torque acting on the coil is given as
 
begin mathsize 14px style straight tau equals straight m cross times straight B equals mBsinθ equals space IlbBsinθ end style
Here, θ is the angle between the magnetic field and the normal to the plane of the coil.
 
Now, the magnetic field is directed perpendicular to the coil. Also, the normal to the coil will be perpendicular to the coil.
 
So, the angle between the normal and the field is 0.
 
Hence, the torque acting on the coil is zero.
Answered by Romal Bhansali | 22 Feb, 2016, 11:26: AM

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