Question

The negatively and uniformly charged non-conducting disc as shown in the figure is rotating clockwise. The direction of the magnetic field at point A in the plane of the disc is:

• A. into the page
• B. out of the page
• C. up the page
• D. down the page

Answer 1

The correct option is A into the page

Disc can be considered as a combination of concentric rings where current is flowing in clockwise direction in each ring. Magnetic field at a point on the plane of the disc produced due to each ring will point into the plane of the paper.