Properties of Light

Light

Travels in straight lines at approximately 300,000 kilometers per second and much faster than sound

Transmission

The passing of light through a material medium, depending on the type of material

Transparent Material

Material that allows light to pass through completely

Translucent Material

Material that allows light to pass through partially

Opaque Material

Material that does not allow light to pass through and instead reflects or absorbs it

Absorption

When a material takes in light and converts it into different forms of energy

Color Perception

Objects appear white when reflecting all light colors, black when absorbing all, and colored based on reflected wavelengths

Green Leaf Absorption

Absorbs all light frequencies except green, which is reflected to the observer's eye

Reflection

When a light ray approaches a smooth polished surface and bounces back

Law of Reflection

The angle of incidence equals the angle of reflection (θᵢ = θᵣ)

Angle of Incidence (θᵢ)

The angle between the incoming light ray and the normal line

Angle of Reflection (θᵣ)

The angle between the reflected light ray and the normal line

Specular Reflection

Reflection off smooth, shiny surfaces resulting in parallel, organized light rays

Diffuse Reflection

Reflection off rough, dull surfaces that scatters light in different directions

Apparent Color

The specific wavelength or color of light that is reflected by an object

Refraction

The bending of light waves due to a change in speed when entering a different medium

Refraction Toward Normal

Occurs when light enters a slower, denser medium (n₂ > n₁)

Refraction Away From Normal

Occurs when light enters a faster, less dense medium (n₁ > n₂)

Snell's Law

The quantitative relationship describing the angles and speed changes in refraction

Angle of Refraction (θ₂)

The angle the refracted light ray makes with the surface normal

Broken Pencil Observation

A visual phenomenon where a pencil appears bent in water due to refraction

Scattering

The splitting and bending of light into several random directions, often due to impurities in a transparent material

Red Sunset Appearance

Atmospheric phenomenon caused by the scattering of light waves

Dispersion

The separation of white light into a full spectrum of component colors

Rainbow

A spectrum formed when sunlight is dispersed by water droplets at specific angles like 42 degrees

Diffraction

The scattering or spreading of a wave as it passes through a slit or around an obstacle

Diffraction Proportionality

Diffraction is proportional to the ratio of wave wavelength to gap width

Interference

When two or more light waves overlap and either increase or decrease in amplitude

Constructive Interference

When identical wave parts like crest and crest meet to increase amplitude and form bright fringes

Destructive Interference

When opposite wave parts like crest and trough meet to cancel out and form dark fringes

Thomas Young's Double Slit Experiment

Demonstrated light interference patterns showing alternating bright and dark fringes

Polarization

The process of transforming unpolarized light waves into polarized light waves

Polarized Lenses

Filters that block horizontal light while allowing vertical light to pass, reducing glare and improving clarity

Wave

A means of transferring energy from one place to another

Transverse Wave

A wave that oscillates at right angles (perpendicular) to the direction of energy transfer

Longitudinal Wave

A wave that oscillates along (parallel) the direction of energy transfer

Crest

The highest point of a transverse wave

Trough

The lowest point of a transverse wave

Amplitude (A)

The maximum displacement of particles from their resting or equilibrium position

Wavelength (λ)

The distance between a point on one wave and the corresponding point on the next wave, measured in meters

Frequency (f)

The number of waves produced or passing a point each second, measured in Hertz (Hz)

Wave Period (T)

The time required to produce one complete wave, calculated as T = 1 / f

Wave Speed Formula

v = f × λ

Frequency Formula

f = v / λ

Wavelength Formula

λ = v / f

Practice Problem 1 Solution

Frequency is 34 Hz (f = 340 m/s ÷ 10 m)

Practice Problem 2 Solution

Wavelength is 5 m (λ = 25 m/s ÷ 5 Hz)

Practice Problem 3 Solution

Wave speed is 500 m/s (v = 50 Hz × 10 m)

Online Activity Question 1

Wavelength is 0.63 meters (λ = 340 m/s ÷ 540 Hz)

Online Activity Question 2

Wave speed is 180,000 m/s (v = 900 Hz × 200 m)

Online Activity Question 3

Frequency is 109.52 Hz (f = 230 m/s ÷ 2.1 m)

Online Activity Question 4

Wave speed is 42 m/s (v = 14 Hz × 3 m)