Yes, light does have an amplitude. In the context of light, the amplitude refers to the strength or intensity of the electric and magnetic fields that make up an electromagnetic wave. The amplitude of a light wave determines the brightness or intensity of the light.
In classical electromagnetism, the amplitude of an electromagnetic wave is related to the maximum value of the electric or magnetic field. For a sinusoidal wave, the amplitude corresponds to the peak value of the field. The square of the amplitude is proportional to the intensity of the light, which is the amount of energy per unit time passing through a given area perpendicular to the direction of propagation.
The amplitude of light can vary, ranging from very low levels (such as in the case of dim light) to high levels (such as in the case of bright light). The amplitude affects various properties of light, including its brightness, the extent of its oscillations, and the amount of energy carried by the wave.
In quantum mechanics, the amplitude of a photon, which is the fundamental particle of light, is also described by a complex number. The complex amplitude of a photon wave function encodes information about the probability of different outcomes when the photon is detected or measured. The magnitude squared of the complex amplitude gives the probability of detecting the photon at a particular location or having a specific energy or momentum.
So, whether in classical or quantum descriptions, light is characterized by an amplitude that determines its intensity, brightness, and probabilistic behavior.