Answer :
Answer:
Explanation:The relationship between electromotive force (emf) of a cell and the potential difference (V) across the terminals of the cell can be understood as follows:
1. **Definition of emf (E)**: The emf of a cell is the maximum potential difference between its two electrodes when no current is flowing through the cell. It represents the energy per unit charge supplied by the cell to move the charge around a complete circuit.
2. **Potential difference (V)**: The potential difference, often denoted as V, is the voltage across the terminals of the cell when it is connected in a circuit and current is flowing through it.
3. **Internal resistance (r)**: Every real cell has an internal resistance due to the resistance of its electrolyte and electrodes. When current flows through the cell, this internal resistance causes a voltage drop inside the cell, reducing the terminal voltage (V) that we measure externally.
The relationship between emf (E), potential difference (V), and the internal resistance (r) of the cell is given by:
\[ V = E - Ir \]
where:
- \( E \) is the emf of the cell.
- \( V \) is the potential difference (voltage) across the terminals of the cell.
- \( I \) is the current flowing through the circuit connected to the cell.
- \( r \) is the internal resistance of the cell.
### Explanation:
- **Emf (E)** is constant for a given type of cell and depends on the chemical reactions occurring within the cell.
- **Potential difference (V)** across the terminals of the cell depends on the emf (E) minus the voltage drop (Ir) due to the internal resistance (r) when current (I) flows through the circuit.
- When no current is drawn from the cell (open circuit condition), \( V = E \) because the internal resistance (r) does not cause any voltage drop.
### Conclusion:
The emf (E) of a cell represents its ideal voltage output when no current is drawn, while the potential difference (V) across the cell's terminals accounts for the voltage drop caused by the internal resistance (r) when current flows. The relationship \( V = E - Ir \) is crucial in understanding how the actual voltage output varies with the current drawn from the cell.
Let the potential difference be V, emf of cell be E, current be I, and internal resistance be R
When no current flows via an external circuit and the circuit is open, the emf (electromotive force) is the potential difference between the terminals of a battery.
The voltage between the terminals of the battery when the current is taken from it to an external source is known as the potential difference.
The potential difference across a cell will be -
[tex] \boxed { \bf \: V = E - Ir}[/tex]
Hence, the potential difference V across a cell of emf E and internal resistance r is V = E - Ir [ANSWER]
Note : Keywords are marked in bold.