Which diagram could represent the electric field lines between two oppositely charged conducting surfaces?

Question 6

Which diagram could represent the electric field lines between two oppositely charged conducting surfaces?

Reference: Past Exam Paper – June 2016 Paper 11 Q29

Solution:

Answer: D.

The electric field lines must always be at right angles to a conducting surface. [A, B and C are incorrect]

In choice A, the field lines are normal the curved surface and not to the square. The same applied to choice C.

The strength of the electric field is represented by how close the lines are to each other.

A uniform field is represented by the equal spacing between the field lines. This is obtained between parallel surfaces (such as two parallel plates). Since one of the surfaces is a curve, we cannot have a uniform field between them (as in B).