It depends on what type of light measurement. See Sources and related links for more information.
light energy
A "ray"
Later
It is called a beam.
A ray.
the light must be coherent - which happens when a single beam of light is split
Reflection.
Laser
It is called a beam.
A Single Beam of Light - 2007 was released on: USA: 14 September 2007 (Estes Park Film Festival)
A line of reflection is a reflected line, often off of a mirror. If a flashlight sends a beam of light at a mirror (the light is called the incident beam), the angle at which it hits the mirror will equall the angle at which the reflected beam of light (called the reflected beam), exits the mirror. This is called the Law of Reflection. This is why light is reflected from a mirror at the same angle at which light struck its surface. A line of reflection is a reflected line, often off of a mirror. If a flashlight sends a beam of light at a mirror (the light is called the incident beam), the angle at which it hits the mirror will equall the angle at which the reflected beam of light (called the reflected beam), exits the mirror. This is called the Law of Reflection. This is why light is reflected from a mirror at the same angle at which light struck its surface.
A ray.
the light must be coherent - which happens when a single beam of light is split
Laser
Reflection.
Yes, light can have a single wavelength. A laser generates a coherent beam of light. It's all one frequency, i.e., it's all the same wavelength.
False.
A chink? A beam? A ray?
the eye
The light from our sun radiates out in all direction as the sun is ball-shaped. The part of light that strikes the earth, forming daylight, is spread over a wide area of the earth that happens to be facing towards the sun at the time. This means that light doesn't travel in a single direction. A laser beam is an example of a concentrated beam of light travelling in a single direction.