# (a) Two point charges and are kept at a distance of in air. Deduce the expression for the electrostatic potential energy of this system.(b) If an external electric field (E) is applied on the system, write the expression for the total energy of this system.

Work done in bringing q2 from infinity to a point

$=q_2\times\frac{1}{4\pi\epsilon_0}\frac{q_1}{r_{12}}$

The potential energy of the system

$=\frac{1}{4\pi\epsilon_0}\frac{q_1q_2}{r_{12}}$

b) Total energy of the system

$=q_1V_1+q_2V_2+\frac{1}{4\pi\epsilon_0}\frac{q_1q_2}{r_{12}}$

## Related Chapters

### Preparation Products

##### Knockout JEE Main April 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
##### Knockout NEET Aug 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
##### Knockout JEE Main May 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
##### Knockout NEET Aug 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-