Question

Define the term "potential difference" between two points in an electric circuit carrying current. Name and define its S.I. unit. Also express it in terms of S.I. unit of work and charge.

Answer 1

Potential Difference

Definition:

Potential difference (V) between two points in an electric circuit carrying current is defined as the work done (W) to move a unit positive charge (q) from one point to the other.

Mathematically: \[ V = \frac{W}{q} \]

S.I. Unit of Potential Difference:

The S.I. unit of potential difference is the Volt (V).

Definition of 1 Volt:

One volt is the potential difference between two points when 1 joule of work is done to move a charge of 1 coulomb: \[ 1 \text{ V} = \frac{1 \text{ J}}{1 \text{ C}} = 1 \text{ J/C} \]

Expression in Terms of S.I. Units:

Since:

• Work (W) is measured in joules (J)
• Charge (q) is measured in coulombs (C)

Therefore: \[ \text{Volt (V)} = \frac{\text{Joule (J)}}{\text{Coulomb (C)}} \]

 

Summary Points:

• Definition: Work done per unit charge
• Mathematical Form: \( \Delta V = \frac{W}{q} \)
• S.I. Unit: Volt (V)
• Dimensional Formula: [ML²T⁻³I⁻¹]
• Base Unit Equivalence: 1 V = 1 J/C