A long cylindrical shell carries positive surface charge σ in the upper half and negative surface charge −σ in the lower half. The electric field lines around the cylinder will look like figure given in: (figures are schematic and not drawn to scale)
(A)(see figure)
(B)(see figure)
(C)(see figure)
(D)(see figure)✓ Correct
Answer: (D)
Solution
Field lines are born on positive charge and die on negative charge, and in an electrostatic field they never close on themselves. With the top half of the cylinder positive and the bottom half negative, the lines must spring out of the upper surface, arc over and plunge into the lower surface. The physically correct picture is the one showing lines leaving the positive upper half and curving down to terminate on the negative lower half.
JEE Main · 2015 · 04 Apr 2015 · Offline · Single correct option
