Chapter summary

The whole chapter in one list.

• Mirrors are of two kinds, plane and curved; curved mirrors are either concave or convex.
• The image of an object in front of a plane mirror is virtual, the same size and upright.
• The incident ray, the reflected ray and the normal lie in the same plane.
• In reflection, the angle of incidence equals the angle of reflection.
• Wherever an object is in front of a convex mirror, the image is small, upright and virtual.
• The bending of light as it passes from one medium into another is refraction.
• From a rarer into a denser medium, light bends towards the normal; from a denser into a rarer medium, away from it.
• In refraction too, the incident ray, the refracted ray and the normal lie in the same plane.

• Going from a denser to a rarer medium, at one angle of incidence the refracted ray runs along the boundary; that angle of incidence is the critical angle.
• When the angle of incidence exceeds the critical angle, the light is reflected back into the denser medium: total internal reflection.
• Light travels along optical fibres by total internal reflection.
• Bi-convex, bi-concave, plano-convex and plano-concave are some kinds of lens.
• Wherever an object is in front of a bi-concave lens, the image is small, upright and virtual.