Question

The distance between the lens and the focal point is called :
A) Reflective index
B) Focal length
C) Radius of curvature
D) Plane of incidence

Answer 1

Hint: The center of the lens or mirror is the point of location where parallel light rays meet after passing through the lens or spreading the mirror.

Complete step by step solution:
Focal length is the distance between the center of a convex lens or a concave mirror and the focal point of the lens or mirror — the point where parallel rays of light meet, or converge. A right lens or mirror will transmit all light rays through a focal point, resulting in a clearer image.

The major focal length of a lens is determined by the index of refraction of the glass, the radius of curvature of the surfaces and the medium in which the lens resides. This can be calculated from the lens-maker's formula of thin lenses.

Additional Information: For a thin double convex lens, the expulsion centers all parallel rays to a single focal point called the focal point. The distance of this point from the lens is the original focal length of the lens. For dual concave lenses where the ray is directed, the original focal length is the distance where the rear-projected ray comes together and gives a negative signal.

For thick lenses made of spherical surfaces, the central distance will be different for different rays and this change is called spherical segmentation. The center length will also vary slightly for different wavelengths and is called chromatic decay.

Note: If a piece of glass or other transparent material takes the appropriate shape, it is possible that a parallel incident ray can either transform into a point or diverge from a point. A piece of glass has a shape called a lens.

A lens is simply a piece of carefully ground or transparent material that reflects a light beam in such a way that an image is formed. Lenses can be thought of as multiple prisms with small refractions, each of which resists light in its image formation. When these prisms work together, they form a bright image centering on a point.