What happens when there's way more than two holes? Created by David SantoPietro.

The index of refraction in a material isn't always the same for every wavelength. This is how prisms split white light into so many colors. Created by David SantoPietro.

Study of physical effects in the vicinity of a black hole as the basis for understanding general relativity, astrophysics, and elements of cosmology. Extension to current developments in theory and observation. Energy and momentum in flat spacetime; the metric; curvature or spacetime near rotating and nonrotating centers of attraction; the Global Positioning System and its dependence on general relativity; trajectories and orbits of particles. Subject has online component and classroom lectures are replaced with online interactions: manipulation of visualization software, access to websites describing current research, electronic submission of homework, and structured online discussions between undergraduates and alumni and with instructors and graduate specialists in the topics covered.

How does a lens form an image? See how light rays are refracted by a lens. Watch how the image changes when you adjust the focal length of the lens, move the object, move the lens, or move the screen.

How do greenhouse gases affect the climate? Explore the atmosphere during the ice age and today. What happens when you add clouds? Change the greenhouse gas concentration and see how the temperature changes. Then compare to the effect of glass panes. Zoom in and see how light interacts with molecules. Do all atmospheric gases contribute to the greenhouse effect?

Create a laser by pumping the chamber with a photon beam. Manage the energy states of the laser's atoms to control its output.

Create a laser by pumping the chamber with a photon beam. Manage the energy states of the laser's atoms to control its output.

In this video David solves a few exmaple problems involving concave and convex mirrors using the mirror equation and magnification equation.

How did scientists figure out the structure of atoms without looking at them? Try out different models by shooting light at the atom. Check how the prediction of the model matches the experimental results.

Lectures, laboratory exercises, and projects in modern optics. Topics: polarization properties of light, reflection and refraction, coherence and interference, Fraunhofer and Fresnel diffraction, imaging and transforming properties of lenses, spatial filtering, coherent optical processors, holography, optical properties of materials, lasers, nonlinear optics, electro-optic and acousto-optic materials and devices, optical detectors, fiber optics, and optical communication.

Do you ever wonder how a greenhouse gas affects the climate, or why the ozone layer is important? Use the sim to explore how light interacts with molecules in our atmosphere.

See how there's actually constructive (rather than just destructive) interference at some points on the screen. Created by David SantoPietro.

Some examples of using the thin lens equation with multiple lenses. Created by David SantoPietro.

Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.

Object Image and Focal Distance Relationship (Proof of Formula). Created by Sal Khan.

Explore an active area of research in optical physics: producing designer pulse shapes to achieve specific purposes, such as breaking apart a molecule. Carefully create the perfect shaped pulse to break apart a molecule by individually manipulating the colors of light that make up a pulse.

See how light knocks electrons off a metal target, and recreate the experiment that spawned the field of quantum mechanics.