Electric Potential

Electric potential (One Volt):

Who is responsible for flow of current in electric circuit? The answer is of course battery. The EMF exert by battery apply a force on electron to move within the conducting wire. The chemical energy stored in a battery provides sufficient voltage. When we connect battery it will move the electron and Cause current in that circuit.

As we already study that the concept of work done in class 9th.

Work done: If an object get displacement under applied an external force are called work done.

In similar manner, the battery provides sufficient energy to move the electron. Consider the electron is at point ‘a’and large negative charge is at point ‘b’. We move the electrons from point a to point b. We know that the electron will repel bythe negative charge at point b. So we will do work done against that force and move the electron from point a to point b. The energy associated with applied external force is stored in the form of work done.

But in this case work done is depend on the charge. In liquid or gases, the charge carriers are positive and negative ions. If a battery connect to a small charge then work done is large. Also if same battery is connect to a large change then work done will small. To avoid  this difficulty we divide work done by charge. So the concept of voltage will not depend on charge.  The work done is same for all type of charges.

Definition of one volt : One volt is defined as one  Joule of work is done to move one Coulomb of charge in a circuit from one point of a battery to another point.

1 Volt = 1 joule / 1 coulomb.

1 V = 1 W / 1 Q.

1 V = J/ C.

The SI unit of voltage is V, named in the memory of famous physicist Alessandro Volta.

More about voltage.

  • It is a source of energy in the circuit.
  • There are so many instruments measure the voltage between two points.
  • Voltage, emf and potential differences are quite same meaning.

Q) How much energy is required to move 5 coulomb charge in a circuit in which applied voltage of 10 V.


Given, V = 10 V,         Q = 5 C

As we know that,

Voltage = Work done / charge

But work done and energy are equal.

Voltage = energy / Charge

Energy = Voltage × Charge.

= 10 V × 5 C.

Energy= 50 Joule.

The energy required to move a charge of 5 C in a circuit in which applied voltage is 10V is 50 Joule.

Q) Calculate work done to move a charge of -6 coulomb in a circuit in which 20 V are connected.

Q) Obtain the work done to move a charge of 2 micro coulomb( 2 x 10⁻⁶) in a potential difference of 4 volt.

Q) Define one volt.

Q) list out the devices which measure voltage.

Q) Complete the following table.

Voltage (V)

Energy/ Work done (J)

Charge (C)

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