Question

1. Define the following term
a) Principal focus of a spherical mirror.
b) Total internal reflection
c) Dispersion
d) Critical angle
e) Power of a lens
f) Mirage​

Answer 1

Answer:

a) The principal focus of a spherical mirror is a point on that spherical mirror's principal axis where parallel light rays intersect (meet) or emerge to deviate after reflection. The Mirror's function is to change the direction in which light travels.

b) Total Internal Reflection (TIR) is a phenomenon in optics, by which light experiences complete reflection at an interface between two media. ... When an incident light ray (red) hits the interface, it is reflected (green) and/or refracted (blue). Figure 1: Snell's law and total internal reflection.

c) Dispersion is a statistical term that describes the size of the distribution of values expected for a particular variable and can be measured by several different statistics, such as range, variance, and standard deviation.

d) Critical angle, in optics, the greatest angle at which a ray of light, travelling in one transparent medium, can strike the boundary between that medium and a second of lower refractive index without being totally reflected within the first medium.

e) The power of a lens is defined as the reciprocal of the focal length. Lens power is measured in dioptres (D). Converging (convex ) lenses have positive focal lengths, so they also have positive power values. Diverging (concave ) lenses have negative focal lengths, so they also have negative power values.

f) A mirage is a sort of optical illusion, a reflection of light that can trick the mind into interpreting the sight as an apparently solid thing. ... Mirage was borrowed into English at the dawn of the 19th century from the French verb mirer ("to look at"), which also gave us the word mirror.

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