Theoretical & Geometric Optics Flashcards

A comprehensive set of vocabulary flashcards covering the principles of theoretical and geometric optics, wave properties, light sources, reflection, refraction, and photometry based on the lecture module.

Optics

The study of light and vision, the nature and behavior of light, and all phenomena related to light.

Geometrical Optics (Ray Optics)

A branch of optics that studies light as rays and deals with straight line propagation and image formation by lenses, mirrors, and prisms.

Physical Optics (Wave Optics)

The study of light in the form of a wave (disturbance traveling through a medium), specifically focusing on diffraction, interference, and polarization.

Quantum Optics (Photon Optics)

The study of light as particles known as quanta or photons, dealing with the interaction of light with matter and wave-particle duality.

Corpuscular Theory

Postulated by Isaac Newton in 1642, it suggests light is composed of minute particles of matter called corpuscles that travel in straight lines.

Undulatory Theory (Wave Theory)

Postulated by Christian Huygens in 1690, it states light is wave motion spreading from a source and propagating through a medium called ether.

Electromagnetic Theory

Postulated by James Clerk Maxwell in 1865, it states light is composed of different wavelengths and propagated in electromagnetic waves.

Quantum Theory (Photon Theory)

Postulated by Max Planck in 1900 and extended by Einstein, it considers radiant energy to consist of discrete units of energy called photons.

Speed of Light in Vacuum

$186,050\,mi/sec$ or $300,080\,km/sec$.

Speed of Light in Air

$186,000\,mi/sec$ or $300,000\,km/sec$ ($3 \times 10^8\,m/s$).

Speed of Light in Water

$140,000\,mi/sec$ or $225,000\,km/sec$.

Speed of Light in Diamond

The slowest speed mentioned at $77,500\,mi/sec$ or $125,000\,km/sec$.

Armand Fizeau

The first man to measure the speed of light through a land experiment known as the Toothed Wheel Experiment (1849).

Leon Foucault

The first person to measure the speed of light in water using the Rotating Mirror Experiment (1850).

Visible Light Spectrum

The small portion of the EM spectrum that can stimulate the human retina, ranging from $380\,nm$ (violet) to $760\,nm$ (red).

High Energy Visible Light (Blue Light)

Visible light ranging from $380$ to $500\,nm$, known for producing higher energy and causing potential retinal damage.

Blue-Violet Light

A harmful range of blue light between approximately $380\,nm$ and $450\,nm$.

Blue-Turquoise Light

A beneficial range of blue light between $450\,nm$ and $500\,nm$ that helps regulate the circadian rhythm.

LASER

Stands for Light Amplification by Stimulated Emission of Radiation; properties include being monochromatic, coherent, and directional.

Incandescence

The emission of light from hot matter, such as in an incandescent lamp, the Sun, or flames.

Luminescence

The emission of light through chemical reactions or excitation of electrons without strong heating, often called "cold light."

Crest

The upward motion or highest point of a wave.

Trough

The downward motion or lowest point of a wave.

Amplitude

The maximum displacement of the vibration of a wave, representing the energy it carries.

Wavelength ($\lambda$)

The distance traveled by light during one complete vibration; the distance between two successive crests or troughs.

Nanometer ($nm$)

A billionth part of a meter ($1 \times 10^{-9}\,m$).

Angstrom ($A$)

A ten-billionth part of a meter ($1 \times 10^{-10}\,m$).

Frequency ($f$)

The number of complete waves generated per second, expressed in Hertz ($Hz$).

Wave Equation

The relationship between velocity ($v$), wavelength ($\lambda$), and frequency ($f$), defined as $v = \lambda f$.

Constructive Interference

Occurs when the crest of one wave meets the crest of another, producing a "supercrest" where waves are in-phase.

Destructive Interference

Occurs when a crest and a trough interfere, decreasing displacement as waves are out of phase.

Diffraction

The apparent bending of waves around obstacles or the spreading out of waves through small openings.

Polarization

The process of transforming unpolarized light (vibrating in multiple planes) into polarized light (vibrating in a single plane).

Vergence ($V$)

The term expressing the convergence or divergence of light, calculated as $V = \frac{1}{d}$ in Diopters ($D$).

Umbra

The central, uniform dark region of a shadow (total shadow) with a sharp border.

Penumbra

The outer annular region of a shadow with partial illumination.

Pinhole Camera (Camera Obscura)

A lensless device that creates a real and inverted image by allowing light through a small aperture.

Specular (Regular) Reflection

Reflection where rays are sent back in a single definite direction from smooth, well-polished surfaces, forming a clear image.

Diffuse (Irregular) Reflection

Reflection from rough surfaces where rays have no definite direction, allowing us to see objects.

First Law of Reflection

States the incident ray, reflected ray, and normal all lie in the same plane at the point of incidence.

Virtual Image

An image that does not physically exist at the location it is seen; formed by the prolongation of rays backward (e.g., in a plane mirror).

Deviation ($\angle d$)

The change in direction of an incident ray, calculated for a plane mirror as $\angle d = 180^{\circ} - 2\angle i$.

Concave Spherical Mirror

A converging mirror that curves inward and has its focal point in front of the mirror.

Convex Spherical Mirror

A diverging mirror that curves outward and always forms a virtual, upright, and diminished image.

Mirror Equation

$\frac{1}{FL} = \frac{1}{p} + \frac{1}{q}$, where $p$ is object distance, $q$ is image distance, and $FL$ is focal length.

Absolute Refractive Index ($n_m$)

The ratio of the velocity of light in vacuum ($v_v$) to the velocity in a medium ($v_m$).

Snell's Law

States that $\sin(\angle i) \times n_1 = \sin(\angle r) \times n_2$.

Critical Angle ($\angle i_c$)

The angle of incidence in a denser medium that results in an angle of refraction of $90^{\circ}$.

Total Internal Reflection (TIR)

Occurs when light traveling from a denser to a rarer medium strikes the interface at an angle of incidence greater than the critical angle ($\angle i > \angle i_c$).

Prism Diopter

The clinical unit of prism power where a $1$ prism diopter prism displaces an image $1\,cm$ at a distance of $1\,m$.

Luminous Flux ($F$)

The total amount of light emitted by a source in a given time, measured in Lumens ($lm$).

Luminous Intensity ($I$)

The amount of light emitted by a source in a specific direction, measured in Candelas ($cd$).

Illumination ($E$)

The amount of light received by a surface, measured in Lux ($lx$) or foot-candles ($ft\,cd$).

Inverse Square Law of Illumination

States that illumination varies inversely with the square of the distance: $E = \frac{I_m}{d^2}$.