Intensity (I)

Definition

Intensity (I) is the power transferred per unit area where the wave is propagating. It quantifies how much energy a wave delivers to a surface per unit time.

5 Must Know Facts For Your Next Test

1. Intensity is proportional to the square of the amplitude of the wave: $I \propto A^2$.
2. The unit of intensity in the International System of Units (SI) is watts per square meter ($W/m^2$).
3. For a spherical wave, intensity decreases with the square of the distance from the source: $I \propto \frac{1}{r^2}$.
4. The formula for intensity is $I = \frac{P}{A}$, where $P$ is power and $A$ is area.
5. In sound waves, higher intensity generally corresponds to louder sounds.

Review Questions

• What is the relationship between intensity and amplitude for a wave?
• How does intensity change as you move farther from a point source of waves?
• What are the units used to measure intensity?

Related terms

Amplitude (A): The maximum displacement or distance moved by a point on a vibrating body or wave measured from its equilibrium position.

Power (P): The rate at which energy is transferred or converted. In waves, it refers to how much energy passes through a given area in a given time period.

Frequency (f): $\text{Number of oscillations or cycles per unit time. Measured in hertz (Hz).}$