TwiddleLab / Courses / Physics
Light and Sight
Lessons
- Light Travels in Straight Lines (5 min): Light travels in straight lines. We draw it as rays.
- Mirrors: Angle In, Angle Out (7 min): Law of reflection: the angle in equals the angle out, both measured from the normal (the line at 90° to the mirror).
- Refraction: Light Bends (7 min): Refraction: light changes direction when it crosses into a material where its speed is different.
- Total Internal Reflection: Light in a Pipe (7 min): Going from glass or water toward air, a ray bends away from the normal. Past the critical angle (about 42° for glass, 49° for water) no light gets out: total internal reflection.
- Lenses Make Images (7 min): A converging lens brings parallel rays together at the focal point F. The distance from the lens to F is the focal length f.
- Your Eye and Glasses (7 min): Your eye is a camera with a flexible lens. It bulges to focus near things: accommodation.
- Splitting White Light: Prisms and Rainbows (7 min): White light is a mix of all colours. Glass bends each colour a little differently: dispersion. Violet bends most, red least.
- Mixing Light vs Mixing Paint (7 min): Additive colour: light adds. Red + green = yellow, green + blue = cyan, red + blue = magenta, all three = white.
- Light Is One Slice of a Spectrum (7 min): Radio, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays are one family: the electromagnetic spectrum. Only the wavelength differs.
- Project: Laser Maze (8 min): At every mirror, angle in = angle out. Turn a mirror by x and the beam turns by 2x; at 45° a mirror turns a beam through 90°.
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