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The diagrams below show regions of equipotentials. A positive charge is moved from A to B in each diagram.

Asked in NEET 2017 · Equipotential surfaces and V-r graphs

• (1) In all the four cases the work done is the same.
• (2) Minimum work is required to move q in figure (I).
• (3) Maximum work is required to move q in figure (II).
• (4) Maximum work is required to move q in figure (III).

Step-by-step solution

Why the other options are wrong

• (2) Assumes the short straight path in (I) needs less work. Work in an electrostatic field depends only on the end potentials, not on the path.
• (3) Assumes the curved equipotentials in (II) change the work; they change the field's shape, not the potentials at A and B.
• (4) Assumes the uneven spacing in (III) changes the work. Spacing changes the local field strength, but V_B-V_A is still 30 V.

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