Optics: Reflection, Refraction, and Wave Phenomena

Comprehensive practicing flashcards covering light theories, geometric optics, mirror and lens behaviors, wave phenomena like interference and diffraction, and optical instruments including the human eye.

Corpuscular theory of light

A theory stating that light is made up of small discrete particles called corpuscles which travel in a straight line with a finite velocity and possess momentum.

The Ray Model of Light

An idealization used for geometric optics where light is represented as rays which are straight lines emanating from an object.

Photons

Discrete, massless units of light that travel in a vacuum at the speed of light, which is $3.00 \times 10^{8}\,\text{m/s}$.

Planck’s constant ($h$)

A universal constant used in the photon model of light with a value of $6.63 \times 10^{-34}\,\text{J s}$ or $4.136 \times 10^{-15}\,\text{eV s}$; used to calculate energy as $E = hf$.

Wave-Particle Duality

The nature of light where it acts as a wave in some experiments and as a particle in others.

Law of reflection

States that the incident ray and the reflected ray are in the same plane normal to the surface, and the angle of reflection equals the angle of incidence ($\theta_r = \theta_i$).

Fermat's Principle of least time

The principle that light travels between two points along the path that requires the smallest transit time.

Diffuse reflection

A type of reflection that occurs when light reflects from a rough surface, causing the angle of incidence to vary across the surface.

Specular reflection

Reflection from a smooth surface, such as a mirror, where the eye must be in a specific position to see the reflected light.

Virtual image

An image formed when light only appears to come from the image location but does not actually pass through it, such as the image in a plane mirror.

Real image

An image formed when light actually comes from the image location to your eyes.

Refraction

The bending of light as it crosses the interface between two different transparent media.

Index of Refraction ($n$)

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

Snell’s law

The equation describing the relationship between the angles of incidence and refraction: $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$.

Dispersion

The phenomenon where the index of refraction depends on the wavelength of light, causing it to spread into a spectrum.

Rayleigh criteria

The principle stating that the amount of molecular scattering of light is proportional to the inverse fourth power of the wavelength of the light ($\lambda^{-4}$).

Huygens’ Principle

A geometric method where all points on a wave front are point sources for the production of spherical secondary waves called wavelets.

Total Internal Reflection

An effect occurring when light meets the boundary between a higher index medium ($n_1$) and a lower index medium ($n_2$) at an angle of incidence larger than the critical angle ($\theta_C$).

Critical angle ($\theta_C$)

The specific angle of incidence for which the refracted light ray moves parallel to the boundary ($\theta_2 = 90^{\circ}$).

Magnification ($M$)

The ratio of the image height ($h'$) to the object height ($h$), defined as $M \equiv \frac{h'}{h}$.

Spherical aberration

A defect in spherical mirrors and lenses where parallel rays do not all converge at exactly the same place due to the target's curvature.

Focal length ($f$)

For a spherical mirror, it is half the radius of curvature ($f = \frac{R}{2}$); it is the distance where parallel rays converge.

Converging Lens

A lens that is thicker in the center than at the edges, bringing parallel rays to a focus.

Diverging Lens

A lens that is thicker at the edge than in the center, causing parallel light rays to spread out.

Diopter ($D$)

The unit of measurement for lens power, defined as the inverse of the focal length in meters ($1\,D = 1\,\text{m}^{-1}$).

Chromatic aberration

A lens defect where different colors focus on different points because the refractive index is wavelength dependent.

Astigmatism

A lens defect occurring when the lens has different curvature radii in different directions.

Coherence

Occurs when two interfering waves have a fixed phase relationship and the same frequency.

Constructive Interference

Occurs when two interfering waves are in phase, reinforcing each other to create a greater amplitude.

Destructive Interference

Occurs when two interfering waves are completely out of phase ($180^{\circ}$), resulting in the waveforms canceling each other.

Young’s Double-Slit Experiment

An experiment measuring light's wave properties by observing the interference pattern (bright and dark fringes) created by light passing through two parallel slits.

Diffraction Grating

A multi-slit device consisting of a large number of equally spaced narrow slits or lines that disperse incident light at specific angles.

Polarization

The state where light's electric fields oscillate in a single plane rather than in any direction perpendicular to propagation.

Malus’s law

Describes the intensity of plane-polarized light transmitted through a polarizer at an angle: $I = I_0 \cos^{2}(\theta)$.

Near point

The closest distance at which the eye can focus clearly, with a normal value of about $25\,\text{cm}$.

Far point

The farthest distance at which an object can be seen clearly, with a normal distance at infinity.

Nearsightedness (Myopia)

A condition where distant objects focus in front of the retina, corrected with a diverging lens.

Farsightedness (Hyperopia)

A condition where nearby objects focus behind the retina, corrected with a converging lens.

Achromatic doublet

A combination of lenses made of two different materials used to reduce chromatic aberration.

Michelson interferometer

An optical device centered around a beam splitter that splits a light beam into two parts and recombines them to form an interference pattern for accurate length measurements.