What measure indicates the energy carried by a wave?

The measure that indicates the energy carried by a wave is intensity. Intensity refers to the amount of energy that passes through a unit area in a given time. It is commonly measured in watts per square meter (W/m²). This concept is crucial in understanding how energy is distributed in wave phenomena such as sound, light, and water waves.

Intensity encompasses both the power of the wave and the area through which it spreads. A higher intensity means that more energy is being transmitted by the wave over a specific area. Therefore, intensity provides a direct link between the wave's energy and how it interacts with its environment, making it the best measure for energy carried by a wave.

In this context, while power (the rate of energy transfer) does relate to wave energy, it does not consider the area over which the energy is spread, which is a key factor in determining the energy per unit area. Density and pressure do not provide insights into the energy carried by waves in the same way that intensity does, as they are more related to the properties of the medium the wave travels through rather than the wave itself.