Exam Question

### Part (a): Difference between Electromotive Force (EMF) and Potential Difference (PD) of a Battery
#### 1. Definition and Fundamental Concept
* **Electromotive Force (EMF, symbol ε or E):** EMF is the total energy supplied by a source (like a battery) per unit of electric charge. It represents the maximum potential difference the source can produce between its terminals when it is in an **open-circuit condition**, meaning no current is being drawn from it. It is the driving force that causes charge to move in a circuit and is a measure of the source's ability to do work.
* **Potential Difference (PD, symbol V):** PD, also known as terminal voltage, is the work done in moving a unit of positive charge from one point to another in an electric circuit. When measured across the terminals of a battery, it is the actual voltage available to the external circuit when the battery is **delivering current (on-load)**.