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An electric dipole consists of charges ± q separated by a distance 2a. It becomes a point (ideal) dipole in the limit

Asked in GSEB Board July 2022 · Dipole moment and dipole field

Answer: (2) 2a→0, q→∞

Step-by-step solution

Idea: a point (ideal) dipole has negligible size but a finite dipole moment p=q×2a.

Negligible size means the separation shrinks: 2a→0.

To keep p=q×2a finite while 2a→0, the charge must grow without limit: q→∞.

So a point dipole is the limit 2a→0, q→∞, with the product q×2a held fixed.

Why the other options are wrong

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