Electric Potential : Point Charge & Multiple Charge System

What is Electric Potential?

Electric potential is defined as the amount of work needed to move a unit charge from a reference point to a specific point against the electric field. When an object is moved against the electric field, it gains some amount of energy which is defined as the electric potential energy. The electric potential of the charge is obtained by dividing the potential energy by the quantity of charge. 

Strength of the electric field depends on the electric potential. It is independent of the fact of whether a charge should be placed in the electric field or not. Electric potential is a scalar quantity. At point charge +q, there is always the same potential at all points with a distance r. Let us learn to derive an expression for the electric field at a point due to a system of n point charges.

The electric potential of an object depends on these factors:

• Electric charge the object carries.
• The relative position with other electrically charged objects.

Electric Potential Due to a Point Charge

The electric potential at a point in an electric field is the amount of work done moving a unit positive charge from infinity to that point along any path when the electrostatic forces are applied. Suppose that a positive charge is placed at a point. The charge placed at that point will exert a force due to the presence of an electric field.  The electric potential at any point at a distance r from the positive charge +q is shown as:

\(\begin{array}{l} V = \frac{1}{4\pi ϵ_0}\frac{q}{r}\end{array} \)

Where r is the position vector of the positive charge and q is the source charge.

As the unit of electric potential is volt, 1 Volt (V) = 1 joule coulomb^-1(JC^-1)

When work is done in moving a charge of 1 coulomb from infinity to a particular point due to an electric field against the electrostatic force, then it is said to be 1 volt of the electrostatic potential at a point.

Watch the video and solve NCERT exemplar Questions in the chapter Electricity Class 10 Science

Electric Potential Due to Multiple Charges

Learn to derive an expression for the electric field at a point due to a system of n point charges. When there is a group of point charges say q₁, q₂, q₃,….q_n is kept at a distance r₁, r_2, r₃,……r_n, we can get the electrostatic potential at any particular point. We can find the electrostatic potential at any point due to each individual charge by considering the other charges absent. We then add all the charges algebraically.

Hence, the electric potential at a point due to a group of point charges is the algebraic sum of all the potentials due to individual charges.

It is given as,

\(\begin{array}{l}V = \frac{1}{4\pi ϵ_0} \sum\limits_{i=1}^{n} \frac{q_i}{r_i}\end{array} \)

Recommended Video:

Important JEE questions on Electrostatic Potential and Capacitance

Know About Electric Potential Energy

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Frequently Asked Questions – FAQs

Q1

What happens to the electric potential when a negative charge is moved from point A to point B?

Electric potential increases.

Q2

What is the SI unit of electric potential?

Joules per Coulomb (Volts)

Q3

Difference in the electric potential is measured using which device?

Voltmeter

Q4

What is the formula to find electric potential difference?

E = W/Q

Q5

Electric potential energy is a scalar or vector quantity?

Scalar quantity

Watch the video and solve complete NCERT exercise questions in the chapter Electricity Class 10

Hope you have learnt about electric potential due to a point charge and to derive an expression for the electric field at a point due to a system of n point charges. Stay tuned with BYJU’S for more exciting articles.