Light – Reflection and Refraction

Flashcards about reflection and refraction of light.

Mirror

A highly polished surface that reflects most of the light falling on it.

Laws of Reflection

The angle of incidence is equal to the angle of reflection; The incident ray, the normal to the mirror at the point of incidence, and the reflected ray all lie in the same plane.

Image formed by a plane mirror

Always virtual and erect. The size of the image is equal to that of the object. The image formed is as far behind the mirror as the object is in front of it. Laterally inverted.

Spherical Mirrors

Mirrors whose reflecting surfaces are spherical.

Concave Mirror

A spherical mirror whose reflecting surface is curved inwards, that is, faces towards the center of the sphere.

Convex Mirror

A spherical mirror whose reflecting surface is curved outwards.

Pole

The center of the reflecting surface of a spherical mirror.

Center of Curvature

The center of the sphere of which the reflecting surface of a spherical mirror forms a part.

Radius of Curvature

The radius of the sphere of which the reflecting surface of a spherical mirror forms a part.

Principal Axis

A straight line passing through the pole and the center of curvature of a spherical mirror.

Principal Focus of a Concave Mirror

The point on the principal axis where rays parallel to the principal axis converge after reflection from a concave mirror.

Principal Focus of a Convex Mirror

The point on the principal axis from which rays parallel to the principal axis appear to diverge after reflection from a convex mirror.

Focal Length

The distance between the pole and the principal focus of a spherical mirror.

Aperture

The diameter of the reflecting surface of a spherical mirror.

Relationship between Radius of Curvature and Focal Length

The radius of curvature (R) is equal to twice the focal length (f).

Refraction of Light

The bending of light as it passes from one transparent medium to another.

Laws of Refraction of Light

The incident ray, the refracted ray, and the normal to the interface of two transparent media at the point of incidence all lie in the same plane. The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given color and for the given pair of media.

Refractive Index

The ratio of the speed of light in a vacuum to the speed of light in the medium.

Optical Density

A measure of how much a medium refracts light; a medium with a higher refractive index is optically denser.

Lens

A transparent material bound by two surfaces, of which one or both surfaces are spherical.

Convex Lens

A lens that converges light rays; it is thicker at the middle than at the edges.

Concave Lens

A lens that diverges light rays; it is thicker at the edges than at the middle.

Principal Axis of a Lens

An imaginary straight line passing through the two centers of curvature of a lens.

Optical Center

The central point of a lens through which a ray of light passes without suffering any deviation.

Aperture of a Lens

The effective diameter of the circular outline of a spherical lens.

Principal Focus of a Convex Lens

The point on the principal axis where rays parallel to the principal axis converge after refraction from a convex lens.

Principal Focus of a Concave Lens

The point on the principal axis from which rays parallel to the principal axis appear to diverge after refraction from a concave lens.

Focal Length of a Lens

The distance of the principal focus from the optical center of a lens.

Object Distance (u)

The distance of the object from its pole.

Image distance (v)

The distance of the image from the pole of the mirror.

Mirror Formula

1/v + 1/u = 1/f

Magnification

m = Height of the image / Height of the object = h′/h

Lens formula

1/v - 1/u = 1/f

Power of a Lens

The reciprocal of its focal length. P = 1/f

Dioptre

The SI unit of power of a lens; equal to the power of a lens with a focal length of 1 meter.