When light travels from one medium to another, such as from air to glass or from air to water, the amplitude of the light wave does undergo a change. This change is described by the phenomenon known as refraction.
Refraction occurs because the speed of light is different in different media. When light encounters a boundary between two different media, such as air and glass, the change in the speed of light causes the light wave to change direction. This change in direction is accompanied by a change in the wavelength and frequency of the light wave while the amplitude is typically unaffected.
According to Snell's law, which governs the behavior of light at the interface between two media, the ratio of the sines of the angles of incidence (the angle between the incident ray and the normal) and refraction (the angle between the refracted ray and the normal) is equal to the ratio of the velocities of light in the two media:
n₁ * sin(θ₁) = n₂ * sin(θ₂)
Where:
- n₁ and n₂ are the refractive indices of the first and second media, respectively.
- θ₁ is the angle of incidence.
- θ₂ is the angle of refraction.
From this equation, we can see that the change in the speed of light, quantified by the refractive indices, affects the direction of the light wave but not its amplitude.
It's important to note that although the amplitude of the light wave doesn't change during refraction, other properties of the light wave, such as intensity or power, can be affected. These changes are related to the energy transfer of the light wave across the boundary and are influenced by factors such as the refractive indices of the media involved and the geometry of the situation.
In summary, when light travels from one medium to another, the amplitude of the light wave remains relatively constant, while the direction, wavelength, and frequency can be altered due to refraction.