The diagrams below show regions of equipotentials. 

 

A positive charge is moved from  A  to  B  in each diagram. 

 

 

• A

  In all the four cases the work done is the same. 

• B

  Minimum work is required to move q  in figure (I)

• C

  Maximum work is required to move  q  in figure (II). 

• D

  Maximum work is required to move q in figure (III).