VITEEE 2017 Paper

The magnetic field is perpendicular to the plane of the paper. Let us consider two diametrically opposite elements. By Fleming's Left hand rule on element AB the direction of force will be Leftwards and the magnitude will be dF = Id/B sin 90° = Id/B

On element CD, the direction of force will be towards right on the plane of the paper and the magnitude will be dF = Id/B.