An electric dipole of moment =(- i-3 j+2 k)× 10^-29 C m at the origin (0,0,0) . The electric field due to this dipole at =+ i+3 j+5 k (note that · =0…
JEE Main 2020 — Physics Electromagnetism
2020mcqmedium
An electric dipole of moment p=(−i^−3j^+2k^)×10−29C m at the origin (0,0,0) . The electric field due to this dipole at r=+i^+3j^+5k^ (note that r⋅p=0 ) is parallel to:
Official previous-year question
Held on 9 Jan 2020 · Verified 6 Jul 2026.
Options
A
(+i^−3j^−2k^)
B
(−i^+3j^−2k^)
C
(+i^+3j^−2k^)
D
(−i^−3j^+2k^)
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Solution
As r⋅p=0, this means that r is perpendicular to p.
For an electric dipole, electric field at equatorial position is antiparallel to p.
⇒E=−λp,
where, λ is an arbitrary positive constant.
⇒E=−λ(−i^−3j^+2k^)×10−29Cm−2
⇒E=λ(i^+3j^−2k^)×10−29Cm−2
For λ=10−291
⇒E=(i^+3j^−2k^)Cm−2
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