Figure shows the path of an electron in a region of uniform magnetic field. The path consists of two straight sections, each between a pair of uniformly charged plates and two half circles. The electric field exists only between the plates

Options

A. Plate `I` of pair A is at higher potential than plate-`II` of the same pair
B. Plate `I` of pair B is at higher potential than plate `II` pf the same pair
C. Direction of the magnetic field is out of the page `[o.]`
D. Direction of the magnetic field in to the page `[otimes]`

Answer

A, B, C

Explanation

Using `-e (vec(V) xx vec(B))` for the regin outside the plates, direction of magnetic field can be found. Inside the plates, net force on the electron is zero hence electric force is opposite to that of magnetic force. Direction of electric field between the plates is opposite to that of direction of forece on the negative (electron) charge.