…and a ray?

Ray Optics -Ray or geometric optics analyzes light while modeling light as a ray.

Spherical Mirrors Concave mirrors look like a cave. They reflect on the inside of the sphere. Convex mirrors look like a bump or blister. They reflect on the outside of the mirror.

Spherical Mirrors

Concave Mirrors

Sign Conventions Note that the reference frame is vertically flipped compared to a traditional reference frame if the mirror is on the right Traditional Mirror on Right

White light consists of many wavelengths, each of which refracts differently through a prism. Dispersion

Dispersion in

for Refraction and Lenses

Geometric Optics Experiments -Draw out configurations of lenses then PREDICT what the ray diagrams for light being shown through these lenses will look like. -Test these predictions with the PHET simulation ‘Geometric Optics’

Electromagnetic Waves (Wave Optics)

Examples

Hypothesize how Electromagnetic Waves with a radio frequency carry information. Materials: PHET  Radio waves & electromagnetic fields Production of Electromagnetic Waves

Representations of EM Waves Electromagnetic waves are oscillations of electric and magnetic fields which propagate through space at the speed of light.

Wavelengths of Visible Light Range from: 400 nm to 700 nm m to m Electromagnetic Spectrum

Common perception of… LightSound Wavelength Frequency Amplitude Electromagnetic Spectrum

The Speed of Light

The story starts with: Galileo Galilei First to hypothesize that light has a finite speed (1564 – 1642)

The Speed of Light (1644 – 1710) Determined the relative speed of light by viewing the orbital period of Io. The period varied by 14 seconds, depending on Earth’s approach. Jupiter Earth Orbit From this he calculated it took 22 minutes for light to travel across the orbit of the Earth. Today’s accepted value is about 16 minutes. Ole Roemer

Albert Michelson (1852 – 1931) In 1926 Michelson was working at the Mount Wilson Observatory in Pasadena California, when he calculated the time light required to make a round trip between two California Mountains 35 Km apart. Determined the speed of light to be: First American to receive the Nobel Prize The Speed of Light

Frequency (f)Wavelength (λ)Section of EM Spectrum m 1x10 15 Hz 5x10 -7 m 3x10 10 Hz 10,000m Electromagnetic Spectrum: c, f, and λ

Polarization – Malus’ Law

Superposition - Interference of Waves The amplitudes of waves combine. Superposition of Waves 60

Interference of Light Waves

Observation Experiment PHET  Waves on a string

Young’s Double Slit Experiment Young’s double slit experiment shows how monochromatic light (EM waves of a single frequency) interferes when diffracted through a double slit.

Double Slit Experiment

Diffraction

Single Slit Diffraction

Diffraction Grating

Explore the photoelectric effect at phet.colorado.edu  Photoelectric Effect

Design Testing Experiments about how objects behave as both waves and particles at phet.colorado.edu  Quantum Wave Interference