Optics, Reflection, Refraction, and Light Properties

Comprehensive vocabulary flashcards covering reflection, refraction, curved and plane mirrors, lenses, wave mechanics, and total internal reflection from optical physics lecture notes.

Light

A form of energy that travels at high speed in a straight path, contains particle and wave properties, and is part of the electromagnetic spectrum detectable by the human eye.

Medium

Any physical substance or matter through which energy can be transferred.

Radiation

The process by which energy, such as light, is transferred through space in the form of electromagnetic waves without requiring a physical medium.

Electromagnetic Spectrum

The entire range of electromagnetic waves, extending from gamma rays with the highest frequency and shortest wavelength to radio waves with the lowest frequency and longest wavelength.

Wavelength ($\lambda$)

The physical distance between consecutive peaks or crests of a wave, measured in metres ($\text{m}$).

Frequency ($f$)

The number of wave cycles that occur per unit of time, measured in hertz ($\text{Hz}$); higher frequency corresponds to higher wave energy.

Universal Wave Equation

The mathematical relationship relating the speed of a wave ($v$) to its frequency ($f$) and wavelength ($\lambda$), expressed as $v = f\times\theta$ or $v = f\times\lambda$, where $v$ is measured in $\text{m/s}$.

Geometric Optics

The study and use of light rays—represented as straight lines with directional arrows—to determine the path of light, especially when interacting with surfaces.

Transparent

A property of a material that allows light to pass completely through, enabling objects behind it to be viewed clearly.

Translucent

A property of a material that permits some light to pass through, but scatters it so that objects behind cannot be seen clearly.

Opaque

A property of a material that prevents any light from passing through, instead either absorbing or reflecting all incident light.

Normal

An imaginary reference line drawn perpendicular ($90^\circ$) to a reflective or refractive surface at the point of incidence.

Law of Reflection

The optical principle stating that the angle of incidence equals the angle of reflection ($\theta_i = \theta_r$), and that the incident ray, reflected ray, and normal all lie within the same plane.

Specular Reflection

The uniform reflection of light rays off a smooth, shiny surface that produces a clear, visible image.

Diffuse Reflection

The irregular scattering of light rays off a dull or uneven surface in multiple directions, preventing the formation of an image.

Virtual Image

An apparent reproduction of an object formed at a location where reflected or refracted light rays do not actually arrive or originate, perceived by the brain behind a mirror or optical boundary.

SALT

The four standard characteristics used to describe an optical image: Size (larger, smaller, same), Attitude (upright or inverted), Location (closer, further, same distance), and Type (real or virtual).

Concave Mirror

A curved mirror where reflection occurs off the inner surface of a spherical curve, converging reflected rays toward a focal point.

Convex Mirror

A diverging curved mirror where reflection occurs off the outer surface of a spherical curve, always producing an image that is smaller, upright, and virtual.

Centre of Curvature ($C$)

The center of the imaginary sphere from which a curved mirror or spherical lens surface is formed.

Principal Axis

The straight imaginary reference line that passes through the centre of curvature and the vertex or optical center of a curved mirror or lens.

Focus ($F$)

The point situated halfway between the centre of curvature ($C$) and the mirror surface or optical center, where incident light rays parallel to the principal axis converge after reflection or refraction.

Refraction

The bending or change in the direction of travel of light that occurs when it passes from one medium into another with a different optical density and speed.

Angle of Refraction

The angle formed between the refracted light ray and the normal line at the boundary interface between two media.

Index of Refraction ($n$)

The dimensionless ratio of the speed of light in a vacuum ($c = 3.00 \times 10^8\,\text{m/s}$) to the speed of light in any other given medium ($v$), defined by $n = \frac{c}{v}$.

Snell's Law

The equation describing the relationship between the indices of refraction and angles of light across two media: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$.

Critical Angle ($\theta_c$)

The specific angle of incidence in a slower medium that causes the refracted light ray to travel along the boundary at an angle of $90^\circ$ relative to the normal in the faster medium.

Total Internal Reflection (TIR)

The complete reflection of all incident light back into the initial medium when light travels from a slower medium toward a faster medium at an angle of incidence greater than the critical angle.

Fibre Optics

A technology using light signals transmitted through glass or high-grade plastic cables (such as Lucite) via repeated total internal reflection due to small critical angles.

Thin Lens Equation

The formula relating object distance ($d_o$), image distance ($d_i$), and focal length ($f$) of a thin lens: $\frac{1}{d_o} + \frac{1}{d_i} = \frac{1}{f}$.

Magnification ($M$)

The dimensionless ratio relating image dimensions to object dimensions, calculated by $M = \frac{h_i}{h_o} = -\frac{d_i}{d_o}$, where a positive value indicates an upright image and a negative value indicates an inverted image.

Converging Lens

An optical lens with a positive focal length ($+f$) that refracts incident rays parallel to the principal axis inward toward the focal point on the opposite side.

Diverging Lens

An optical lens with a negative focal length ($-f$) that causes parallel incident light rays to spread apart, always producing an image that is smaller, upright, virtual, and closer to the lens.