Electric Dipole

A dipole is a separation of positive and negative charges, and can be represented as a pair of point charges, with opposite charges.

Let $d$ be the distance between two point charges, $A$ and $B$ , with charge $+ q$ and $- q$ respectively. Then the dipole Moment is defined as:

Electric Dipole Moment

$μ_{E} = q d$

$μ_{E} or p$ = Dipole moment vector, pointing from negative to positive charge (in $Cm$ )
$d$ = Displacement Vector between $A$ and $B$ (in $m$ )
$q$ = Magnitude of Charge on $A$ and $B$ (in $C$ )

300

E_{Y} = k_{e} \times (\frac{q}{( y - \frac{d}{2} ) ^{2}} + \frac{- q}{( y + \frac{d}{2} ) ^{2}})

= q \times k_{e} \times \frac{2 y d}{( y + \frac{d}{2} ) ^{2} ( y - \frac{d}{2} ) ^{2}}

However, if the distance from the dipole, $y$ is much greater than $d$ , we can safely ignore $d$ .

E_{Y} = q k_{e} \times \frac{2 y d}{y ^{4}} = k_{e} \times q \times \frac{2 d}{y ^{3}} = \frac{2 k _{e} q d}{y ^{3}}

Recall that the electric dipole moment $p$ is given by:

p = q d

E_{Y} = \frac{2 p \times k _{e}}{y ^{3}}

Questionably Accurate Notes