Question

What is PD and why is it lower than EMF?

Answer 1

Hint: In this question, we need to describe the concept of potential difference (PD) and also we have to explain why it is lower than electromotive force (EMF). The potential difference between two nodes in a circuit is the change in the total energy that electric charges have. Potential differential (PD) is also known as voltage and therefore is measured in volts (V).

Complete step by step solution:
Let us discuss the concept of potential difference. A potential difference is the work necessary to move a charge from one location to the other. There has to be a potential difference in current for a charge to flow across two locations. An alternative word for it is the potential energy differential per unit charge or voltage. The metric of potential difference (V) is the Volt.

Also, we know that a potential difference is defined as the quantity of work necessary to shift a unit positive charge from one point to the other.Mathematically, it is denoted by,
\[1{\text{ }}\dfrac{\text{Joule}}{\text{Coulomb}} = 1{\text{ volt}}\]
Here, we can define 1 volt as the potential difference between two places in a current-carrying conductor whenever one joule of effort is done to move one coulomb of charge from one point to another.

Thus, we can say that just because some energy is consumed in the flow of charge through the electrolyte of the cell whenever charges flow in circuitry, a potential difference is always smaller than EMF.

Therefore, the potential difference is the difference in electric potential between two points in circuitry and is lower than EMF.

Note: Here, students generally think that the concepts of potential difference and electromotive force are the same. The quantity of energy delivered to each coulomb of charge is defined as the electromotive force while the potential difference is the amount of energy that one coulomb of charge consumes. The electromotive force is independent of the internal resistance of the circuit. The potential difference is proportional to the resistance of the circuit.