InterviewSolution
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InterviewSolution
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(a) Define electrostatic potential at a point. Write its SI unit. Three charges q_(1), q_(2) and q_(3) are kept rspectively at points A, B and C as shown in figure Write the expression for electrostatic potential enery of the system. (b) Depict the equipotential surfaces due to (i) an electric dipole. (ii) two identical negative charges separated by a small distance. |
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Answer» SOLUTION :(a) Electric potential at a point in an electric field is equal to the amount of work done by the EXTERNAL force (against the electric field) in order to bring a unit positive test charge (without acceleration) from infinity to that point. MATHEMATICALLY, electrostatic potential at a point A is given by `V_(A)=(W_(oo)rarrA)/(q_(0))`, where `W_(oo rarrA)` is the amount of work doen in order to carry a test charnge `q_(0)` from `oo` to the point A. Value of test charge should be as small as possible. SI unit of electric potential is volt (V). Potential is said to be 1 volt if a work of 1 J is being done to bring a positive charge of 1 C from infinity to that point. Expression for potential eneryg. U of hte combination of three charge is : `U=(1)/(4pi in_(0))[(q_(1)q_(2))/(r_(12))+(q_(1)q_(3))/(r_(13))+(q_(2)q_(3))/(r_(23))]` (b) (i) Equipotential surfaces due to an electric dipole are shown below :  (ii) Equipotential surface due to two identical charges separated by a small distance .d. are shown below : 
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