Why are the equipotential lines of a dipole more dense between the electrodes than behind the electrodes.

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http://www.pstcc.edu/departments/natural_behavioral_sciences/Web%20Physics/E2020D0103.gif

Question

Why are the equipotential lines of a dipole more dense between the electrodes than behind the electrodes. 

Image for reference:
http://www.pstcc.edu/departments/natural_behavioral_sciences/Web%20Physics/E2020D0103.gif

anonymous · Answer

Think about it. If they were separate they'd just be spread out evenly right but when you add them together on the same field each charge responds to the other causing a quicker change in electric potential.

vincent-lyon.fr · Answer

Because this is where the electric field is strongest, due to the near presence of both charges.