Light: Reflection and Refraction Lecture Notes

Vocabulary flashcards covering the fundamental concepts, laws, and formulas of light reflection and refraction based on the provided Physics lecture notes.

Ray of light

The straight-line path of light, often indicated by a line with an arrow.

Diffraction of light

The phenomenon where light has a tendency to bend around a very small opaque object on its path instead of traveling in a straight line.

Modern quantum theory of light

A theory that reconciles the particle properties of light with its wave nature, stating that light is neither purely a 'wave' nor a 'particle'.

Laws of reflection

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

Virtual image

An image that cannot be obtained on a screen and is always erect in the case of a plane mirror.

Laterally inverted

The property of an image formed by a plane mirror where the left side of the object appears as the right side of the image.

Spherical mirror

A mirror whose reflecting surface is part of the surface of a sphere.

Concave mirror

A spherical mirror with a reflecting surface that is curved inwards, facing towards the centre of the sphere.

Convex mirror

A spherical mirror with a reflecting surface that is curved outwards.

Pole ($P$)

The centre of the reflecting surface of a spherical mirror, which lies on the surface of the mirror.

Centre of curvature ($C$)

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

Radius of curvature ($R$)

The radius of the sphere of which the reflecting surface of a spherical mirror forms a part, equal to the distance $PC$.

Principal axis

An imaginary straight line passing through the pole and the centre of curvature of a spherical mirror; it is normal to the mirror at its pole.

Principal focus ($F$)

The point on the principal axis where rays parallel to the axis meet (concave) or appear to come from (convex) after reflection.

Focal length ($f$)

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

Aperture

The diameter of the circular outline of the reflecting surface of a spherical mirror.

Relationship between $R$ and $f$

For spherical mirrors of small apertures, the radius of curvature is twice the focal length, expressed as $R = 2f$.

Mirror formula

The mathematical relationship between object distance ($u$), image distance ($v$), and focal length ($f$), expressed as $\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$.

Magnification ($m$)

The ratio of the height of the image ($h'$) to the height of the object ($h$), also expressed as $m = \frac{h'}{h} = -\frac{v}{u}$.

Refraction of light

The phenomenon of the change in direction of propagation of light when it travels obliquely from one transparent medium to another.

Snell’s law of refraction

The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for a given pair of media: $\frac{\sin(i)}{\sin(r)} = \text{constant}$.

Refractive index ($n$)

A value representing the extent of change in direction of light in a medium, linked to the relative speed of propagation of light in different media.

Absolute refractive index

The refractive index of a medium with respect to vacuum or air, calculated as $n_m = \frac{c}{v}$, where $c$ is the speed of light in air and $v$ is the speed in the medium.

Optical density

The ability of a medium to refract light; the medium with the larger refractive index is optically denser, where light travels slower.

Convex lens

A transparent material with two surfaces bulging outwards, which converges light rays; also called a converging lens.

Concave lens

A transparent material bounded by two surfaces curved inwards, which diverges light rays; also called a diverging lens.

Optical centre ($O$)

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

Lens formula

The relationship between object distance ($u$), image distance ($v$), and focal length ($f$) for a lens: $\frac{1}{v} - \frac{1}{u} = \frac{1}{f}$.

Power of a lens ($P$)

The degree of convergence or divergence of light rays achieved by a lens, defined as the reciprocal of its focal length: $P = \frac{1}{f}$.

Dioptre ($D$)

The SI unit of power of a lens; $1\,D$ is the power of a lens whose focal length is $1\,metre$ ($1\,D = 1\,m^{-1}$).