The electric field at a point on the equatorial plane at a distance r from the centre of a dipole having…

The electric field at a point on the equatorial plane at a distance r from the centre of a dipole having dipole moment p is given by (r>> separation of two charges forming the dipole, ϵ0- permittivity of free space)
  1. E=P4πϵ0r3
  2. E=2P4πϵ0r3
  3. E=-P4πϵ0r2
  4. E=-P4πϵ0r3

Solution

Use the concept of potential gradient, then the relation, Er=-dVdrEθ=-1r×dVdθ &V=KPr2cosθ, for general point, 
Eθ=-1r×dKPr2cosθdθ E=-KPr31+3cos2θ, for the equatorial position, θ=90°

E=-kPr3=-P4πϵ0r3.

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Asked in: NEET 2020 (Phase 2)

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