Electric Field Due to an Electric Dipole Two charges `pm5muC` are placed 5 mm apart. Determine the electric field at
a point X on the axis of dipole 10 cm away from its centre O on the side of the positive charge as shown in Fig. (a).

Explanation

Given, `q=pmCpm5xx10^(-6)C`
`2l=5" mm "=5xx10^(-3)m`
`x=OX=OY=10" cm "=10xx10^(-2)`m,
`E_(X)=?` and `E_(Y)=?`
`:.` Dipole moment,
`p=qxx2l=5xx10^(-6)Cxx5xx10^(-3)m`
`=25xx10^(-9)" C-m"`
Now, find out the electric field at point X on the axial line of dipole :
`E_(X)=(2px)/(4piepsilon_(0)(x^(2)-l^(2))^(2))`, along BX produced
Since, `l ltltx`, therefore
`E_(X)=(2p)/(4piepsilon_(0)x^(3))=(2xx25xx10^(-9)xx9xx10^(9))/((10xx10^(-2))^(3))`
`=4.5xx10^(5)"NC"^(-1)` , along BX produced