Question

The electric intensity due to a dipole of 10 cm and having a charge of $500\mu C$, at a on the axis at a distance $20cm$

• A. $6.25\times {10}^{7}N/C$
• B. $6.28\times {10}^{7}N/C$
• C. $1.31\times {11}^{11}N/C$
• D. $20.5\times {10}^{7}N/C$

Answer 1

The correct option is A $6.25\times {10}^{7}N/C$

Lenght of dipole $=10cm=0.1m$

Change on dipole $q=500cm$

$=500\times {10}^{-6}C$

distance of the point on the axis of the midpoint of the dipoler $=20+5=25cm$

$=0.25m$

$E=\frac{1}{4\pi {\epsilon }_0}\frac{2q.2l}{(r^2-l^2{)}^2}=$

$=9\times {10}^9\times \frac{2(500\times {10}^{-6}\times 0.1)\times 0.25}{\left[\right(0.25{)}^2-(0.05{)}^2{]}^2}$

$=\frac{225\times {10}^3}{3.6\times {10}^{-3}}=6.25\times {10}^{2}N/C$