Question

What is PD and why is it lower than EMF?

Answer 1

1. The potential difference between any two points is defined as the amount of work done in moving a unit charge from one point to another.
2. EMF is the maximum potential difference when a circuit is not connected.
3. Potential difference is the difference when a circuit is closed.
4. A potential difference is always lower than an EMF.
5. Because when charges flow in a circuit, some energy is spent in the flow of charge through the electrolyte of the cell.
6. EMF is defined as the work done on a unit charge
7. The formula for electrical potential difference
   $E=\frac{W}{Q}$
   Where $E$ is the potential difference, $W$ is the work done, $Q$ is a unit charge
8. The potential difference measured in volts is given by
   $V=IR$
   Where $V$ is the potential difference, $I$ is current and $R$ is a resistance.
9. Potential difference and Emf relation:
   $\mathrm{E}=\mathrm{V}-\mathrm{Ir}$
   where, $V$ is the potential difference, $I$ is the current, $E$ is the potential difference of the cell and $Ir$ is the lost voltage of the circuit ( Due to internal resistance of battery).