Optical fibres consists of inner part called core and outer part called cladding(or) sleeving.

The entire light is reflected back into the denser medium itself. This phenomenon is called total internal reflection.

The phenomenon in which a part of light from a source undergoing reflection and the other part of light from the same source undergoing refraction at the same surface is called simultaneous reflection or simultaneous refraction.

The angular separation between the two extreme colours (violet and red) in the spectrum is called the angular dispersion.

(i) The incident light is assumed to be monochromatic (single colour).
(ii) The incident ray of light is very dose to the principal axis (paraxial rays).

(i) Light must travel from denser to rarer medium,
(ii) Angle of incidence in the denser medium must be greater than critical angle (i > i_c).

The plane through the focus and perpendicular to the principal axis is called the focal plane of the mirror.

The distance between the pole and the focus is called the focal length (f) of the mirror.

The middle point on the spherical surface of the mirror (or) the geometrical center of the mirror is called pole (P) of the mirror.

The radius of the sphere of which the spherical mirror is a part is called the radius of curvature (R) of the mirror.

The centre of the sphere of which the mirror is a part is called the center of curvature (C) of the mirror.

If the reflection takes place at the convex surface, it is called a convex mirror and if the reflection takes place at the concave surface, it is called a concave mirror.

The bouncing back of light into the same medium when it encounters a reflecting surface is called reflection of light.

Yes. It is possible for two lenses to produce zero power. Both the surfaces of lenses are equally curved, i.e. R₁ = R₂ and hence Power (P) = (µ – 1) \(({\frac{1}{R_1} - {\frac{1}{R_2}}})\) = 0

The angle between the incident ray and deviated ray of light ray is called Angle of deviation due to reflection. d = 180 - 2i