Question

Laser light is considered to be coherent because it consists of
(A) Many wavelengths
(B) Uncoordinated wavelengths
(C) Coordinated waves of exactly the same wavelength
(D) Divergent beams

Answer 1

Hint: We know that lasers produce a very narrow beam of light that is useful in many technologies and instruments. The light emitted from a laser is monochromatic, that is, it is of one wavelength (colour). In contrast, ordinary white light is a combination of many different wavelengths (colours). Laser light from gas or crystal lasers is highly collimated because it is formed in an optical cavity between two parallel mirrors which constrain the light to a path perpendicular to the surfaces of the mirrors. In practice, gas lasers can use concave mirrors, flat mirrors, or a combination of both.

Complete step by step answer
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Spatial coherence also allows a laser beam to stay narrow over great distances (collimation), enabling applications such as laser pointers and lidar.
We know that laser light is considered to be coherent because it consists of waves of exactly the same wavelength in phase. Lasers are used in optical disk drives, laser printers, barcode scanners, DNA sequencing instruments, fibre-optic, semiconducting chip manufacturing (photolithography), and free-space optical communication, laser surgery and skin treatments, cutting and welding materials, military and law enforcement devices.
Hence, laser light is considered to be coherent because it consists of coordinated waves of exactly the same wavelength.

So, the correct answer is option C.

Note: Buying a laser used to be easy because of the limited choices, but it now requires more research. Lasers now come in different colors—green, red, blue and yellow—and function in different ways, too. Green light lasers are the most common and popular today. A laser beam is not just focused light. A laser beam is coherent light. In fact, the word "laser" is actually an acronym that stands for "Light Amplification by Stimulated Emission of Radiation". A laser beam is coherent light, not focused light. Each photon in the laser is synchronously coherent with each other, adding up energy to the beam instead of scattering the energy each on its own as a common lamp does. So the beam will be so intense over a small region of matter to the point of delivering energy to it so it breaks (burns) apart.