Question

A charged, insulating cylinder is set so that its axis is perpendicular to the page, so that the cylinder's cross-section is represented by the circle shown in the diagram.
The cylinder is moving in a direction along its axis, so that the region around the cylinder contains both electric and magnetic field. At selected points, the electric field is represented by a green arrow and the magnetic field is represented by a blue arrow.
Which of the following must be true about the cylinder and its motion?

• A. The cylinder is positively charged and moving out of the page.
• B. The cylinder is positively charged and moving into the page.
• C. The cylinder is negatively charged and moving out of the page.
• D. The cylinder is negatively charged and moving into the page.

Answer 1

The correct option is A The cylinder is positively charged and moving out of the page.

As the electric field lines are pointing toward he cylinder therefore cylinder has a negative charge .

Now if it is moving into the page , the direction of current (opposite to negative charge ) will be out of the page hen by Right hand thumb rule , direction of magnetic field will be along the curl of the fingers i.e. as given in the diagram (anticlockwise ) .