What is a characteristic of light in a laser beam?

A characteristic of light in a laser beam is that it is monochromatic and coherent. Monochromatic means that the light consists of a single wavelength or color, which gives laser light its distinct and pure hue. This property allows it to produce a very concentrated and intense beam.

Coherence refers to the phase relationship of the light waves in the beam; in a laser, the light waves are in phase with each other over long distances. This coherence is what allows lasers to focus tightly and produce a high-intensity output, making them effective for applications such as cutting, illuminating, and communication.

In contrast, other types of light sources, like incandescent bulbs or LEDs, emit multiple wavelengths and are incoherent, leading to a broad spectrum of colors and a lack of phase alignment. The characteristic of variable phase is also not applicable to lasers, as the phase of the light waves in a laser is highly organized and synchronized. This combination of being monochromatic and coherent is what sets laser light apart from other forms of illumination.