Light and Optics Lecture Notes

Comprehensive vocabulary flashcards covering the physics of light, electromagnetic fields, wave properties, optics, and atmospheric phenomena as discussed in the lecture.

Light

A wiggling electric field and magnetic field combined.

Electromagnetic Field

Created when moving electrified fields and magnetic fields oscillate together at the speed of light.

Visible Light Frequency Range

$4.3 \times 10^{14}$ to $7 \times 10^{14}$.

Hertz

The unit used to measure the 'wiggliness' or frequency of light.

Wavelength Relationship

The relationship between wave speed, frequency, and wavelength expressed as $V = f\lambda$ or $C = f\lambda$.

Resonant Frequency (Glass)

Glass is resonant with ultraviolet light; the atoms hold onto it and the vibrations turn into heat.

Opaque Objects

Objects that absorb light without remitting it, converting the energy into kinetic energy and heat.

Umbra

A sharp shadow created when an object blocks a pointed light source.

Penumbra

A partial shadow with lighter edges created by a large light source.

Blackbody Radiation

Heat-dependent light production where higher temperatures result in more colors (infrared and blue) on the spectrum.

Electron Volt ($eV$)

A unit of energy; according to the notes, $1\,eV = 1.6 \times 10^{-16}\text{ joules}$ (noted on Page 4) or $1.6 \times 10^{-19}\text{ J}$ (noted on Page 5).

Energy of a Photon ($E_p$)

Calculated by the formula $E_p = hf$ or $E_p = \frac{hc}{\lambda}$.

Planck’s Constant ($h$)

A constant value given in the text as $6.63 \times 10^{-63}$.

Subtractive Primary Colors

Yellow, magenta, and cyan.

Resonance (Color)

The process where materials have natural frequencies at which they absorb and reemit light, determining their color.

Absorption Spectrum

An identification spectrum for elements made of resonance lines, Balmer lines, and rotation-vibration bands.

Speed of Sound

$343\text{ meters/second}$, which is significantly slower than the speed of light.

Redshift

Occurs when light moves farther away, causing a lower frequency and spectral lines to move to the right.

Blueshift

Occurs when light moves closer, causing a higher frequency and spectral lines to move to the left.

Polarized Light

Light that wiggles in only one plane, described by the intensity formula $I = I_0(\cos(\theta))^2$.

Constructive Interference

Occurs when light waves align crest to crest, increasing the wave height.

Destructive Interference

Occurs when a trough meets a crest, equalizing the waves and decreasing wave height.

Double Slit Equation

$y = \frac{n\lambda(x)}{d}$, where $y$ is the distance between bright lines and $d$ is the distance between slits.

Wave Particle Duality

The theory that light acts as both a particle (photons) and a coherent wave.

AM (Amplitude Modulation)

Radio waves that change height to travel fast and long distances for communication.

FM (Frequency Modulation)

Radio waves that change closeness for clearer sound without interference, used for music.

Index of Refraction ($n$)

The ratio of the speed of light in a vacuum to the speed of light in a material ($n = \frac{c}{v}$).

Snell’s Law

The formula $n_1\sin(\theta_1) = n_2\sin(\theta_2)$ used to describe refraction.

Scattering

The process by which atmospheric molecules receive and reemit sunlight; smaller molecules scatter higher frequencies like blue.

Greenflash

The phenomenon where only green light passes through the atmosphere at sunset because red light is blocked by the Earth.

Fermat’s Principle of Least Time

Light travels the path that requires the least time, rather than the shortest distance.

Specular Reflection

Reflection that occurs on smooth surfaces where light bounces at equal angles.

Diffuse Reflection

Reflection on rough surfaces that scatters light in many directions, making objects visible from all angles.

Critical Angle

The specific angle (e.g., $48^{\circ}$ for water) at which light will no longer leave the medium but reflect perfectly back into it.

Dispersion

The separation of white light into a rainbow of colors using an angled triangular prism.

Huygens' Principle

The principle that wavefronts are made up of tinier waves called wavelets.

Diffraction

The bending of light around an object or edges of an opening that is not due to reflection or refraction.