Question

The focal length of a lens is greatest for which color?
A. Violet
B. Red
C. Yellow
D. Green

Answer 1

Hint: To answer this question, we first need to understand what lens is. A lens is a transmissive optical device that employs refraction to focus or disperse a light beam.A simple lens is made up of a single transparent piece, whereas a compound lens is made up of numerous simple lenses placed along a common axis.

Complete answer:
The focal length of an optical system is the inverse of the system's optical power; it measures how strongly the system converges or diverges light. A system with a positive focal length converges light, while one with a negative focal length diverges light.A system with a shorter focal length bends the rays more sharply, bringing them closer to the focus or diverging them faster.

A positive focal length is the distance over which initially collimated rays are brought to a focus for the special case of a thin lens in air, or conversely, a negative focal length specifies how far in front of the lens a point source must be positioned for the specific case of a thin lens in air. Greatest focal length - High frequency waves, such as blue, travel the slowest in any medium when contrasted to low frequency waves, such as red. (With the exception of vacuum, where they all travel at the same speed)

As a result, high frequency waves, such as blue, bend more (have a higher refraction or refractive index) than low frequency waves, such as red. When blue color is incident on a convex (or concave) lens, it bends more and so converges (or diverges) closer to the lens. As a result, blue has a shorter focal length than red color.So, we conclude that Because wavelength is proportional to focus length, maximum focal length for red light is proportional to wavelength.

Hence, the correct answer is option B.

Note: The eye's nominal focal length is around 17 mm, however it changes depending on accommodation. The nature of human binocular vision, which employs two lenses rather than one, as well as post-processing by the cortex, differs significantly from the creation and rendering of a photograph, video, or film.