# Electricity Calculation: Potential Difference Across a Filament Lamp

What is the potential difference across a 24 W, 12 V filament lamp when a current of 0.8 A flows through it?

The potential difference across the lamp when a current of 0.8 A flows through the lamp is 2 V. The resistance of the lamp is 2.5 Ω for currents up to 0.8 A. We can calculate the potential difference across the lamp using Ohm's Law, which relates potential difference (V), current (I), and resistance (R) in a circuit. The formula for Ohm's Law is V = IR, where V is the potential difference, I is the current, and R is the resistance.

## Ohm's Law Calculation

**Ohm's Law formula:**V = IR

Given:

- Current (I) = 0.8 A
- Resistance (R) = 2.5 Ω

V = 0.8 A x 2.5 Ω

V = 2 V

Therefore, the potential difference across the lamp when a current of 0.8 A flows through it is 2 V.

This calculation confirms that the potential difference across the lamp is in line with Ohm's Law. When the current increases, the potential difference also increases proportionally, given a constant resistance.