Question

The failure of the paraxial and marginal rays passing through the same point on reflection at a spherical mirror or refraction through a lens is known as:
A. Chromatic aberration
B. Spherical aberration
C. Astigmatism
D. Coma

Answer 1

To solve this problem we will firstly find out different phenomena that occurs in ray optics, what are changes occur when it undergoes refraction, also by using this concept we can find out the failures of paraxial and marginal rays when passes through the same point on reflection at a spherical mirror or refracted through lens which phenomena occurs, by using this concept we can easily approach our answer.

Complete step by step answer:
Spherical aberration – type of aberration present in spherical surfaces. Lenses and curved mirrors are not non-spherical because spherical surfaces are always easy to make. We can observe a deviation in which image quality is often compromised. Light rays reflect or refract towards the centre always even if they are not centralised.
Ray optics- Ray optics is also called geometrical optics, is a model of optics that describes light propagation in terms of rays. The rays in geometric optics are used for approximating the path along which the light propagates under certain circumstances.
Refraction: Refraction is the change in the direction of a wave passing from one medium to another in it. It is one of the most commonly observed phenomena that occurs, but other waves like sound waves and water waves also experience refraction.
When the light crosses the boundary between two different media, deviation of light happens,resulting in refraction such that there is a change in wavelength and speed of light.
Optical device shows an optical effect named as spherical aberration. It is seen in (lens, mirror etc.) that happens due to the rise in refraction of light rays.Now as they hit a lens or a reflection of light rays when they hit on the mirror near the edge, in comparison with those that hit close to the centre. When marginal ray and paraxial rays do not converge at the same point, on a spherical surface, either mirror or lens, it is known as the spherical aberration.

So, the correct answer is “Option B”.

Note: Different types of spherical lenses are:
Convex or Converging Lenses: They are thick in the middle and thin at the edges. Also, It can be reduced by carefully choosing the surface curvatures for a particular application. For instance, a plano-convex lens, which is used to focus a collimated beam, produces a sharper focal spot when used with the convex side towards the beam source.
Concave or Diverging Lenses: They are thin in the middle and thick at the edges, also an intrinsic defect with any mirror that takes on the shape of a sphere. Which forbids the mirror from focusing all the incident light from the same location on an object to a precise point.