Q. Two charges $+ 3.2 \times 10^{- 19}C$ and $- 3.2 \times 10^{- 9}C$ kept $2.4\ \mathring{\mathrm{A}}$ apart forms a dipole. If it is kept in uniform electric field of intensity $4 \times 10^{5}\ volt/m$ then what will be its electrical energy in equilibrium
A) $+ 3 \times 10^{- 23}J$
B) $- 3 \times 10^{- 23}J$
C) $- 6 \times 10^{- 23}J$
D) $- 2 \times 10^{- 23}J$
Explanation
(b) Potential energy of electric dipole
$U = - pE\cos\theta = - (q \times 2)E\cos\theta$
$U = - \left( 3.2 \times 10^{- 19} \times 2.4 \times 10^{- 10} \right)4 \times 10^{5}\cos\theta$
$U = - 3 \times 10^{- 23}$ (approx.)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.