A square shaped current loop of side length L and carrying current I lies in a uniform magnetic field B acting perpendicular to the plane of squre loop and directed inward. The net magnetic force acting on current loop is

Options

A. lBL
B. 4 lBL
C. zero
D. 2lBL

Answer

C

Explanation

Let the current is flowing in anti-clockwise direction as shown in figure.

Now, magnetic force on `AD=F_(1)=ilB` inwards (By Fleming’s left hand rule).
Similarly, magnetic force on `BC=F_(2)=ilB` inwards
Since two forces are equal in magnitude and opposite in direction, therefore, they cancel out each other.
Also, magnetic force on `CD=F_(3)=ilB` inwards (By Fleming’s left hand rule)
Similarly, magnetic force on `AB=F_(4)=ilB` inwards
Again, two forces are equal in magnitude and opposite in direction, therefore, they cancel out each other.
So, the net force on the current loop is 0.