Final answer:
When a light wave has high amplitude, it means that the light's intensity is brighter.
Step-by-step explanation:
The intensity of a light wave is directly related to its amplitude. When a light wave has a high amplitude, it means that the wave has a large maximum displacement from its equilibrium position. This results in a higher intensity of the light, which is perceived as brighter. Amplitude and intensity are directly proportional, meaning that as the amplitude increases, the intensity increases as well.