How does the field or potential intensity vary with distance $r$ in 'Wave Optics'?

medium MCQ Class 12 · Physics · Wave Optics

It follows an inverse-square law relationship $\propto 1/ r^{2}$ or dipolar $\propto 1/ r^{3}$
It increases linearly with increasing distance $r$
It remains strictly constant at all spatial coordinates
It varies exponentially as $e^{+ r}$

Answer

It follows an inverse-square law relationship

\propto 1/ r^{2}

or dipolar

\propto 1/ r^{3}

The correct answer is It follows an inverse-square law relationship $\propto 1/ r^{2}$ or dipolar $\propto 1/ r^{3}$ — Dipole configurations decrease faster ( $E \propto 1/ r^{3}$ ) due to opposite charge cancellation.

Step-by-step solution

Point charges/sources produce inverse-square fields ( $E \propto 1/ r^{2}$ ).
Dipole configurations decrease faster ( $E \propto 1/ r^{3}$ ) due to opposite charge cancellation.

Concept tested: Spatial Distance Dependence

Published 28 August 2026 · How this solution was prepared and checked

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How does the field or potential intensity vary with distance r in 'Wave Optics'?

Step-by-step solution

How does the field or potential intensity vary with distance $r$ in 'Wave Optics'?