Boyle's Law states that the pressure of a gas is inversely proportional to its volume when the temperature is held constant. The formula for Boyle's Law can be expressed as:
\[ P_1 V_1 = P_2 V_2 \]
Where:
- \( P_1 \) = initial pressure
- \( V_1 \) = initial volume
- \( P_2 \) = final pressure
- \( V_2 \) = final volume
This means that if the volume of a gas decreases, the pressure increases, provided the temperature remains constant, and vice versa.