The Concave Mirror — A Swinging Reflection
A concave mirror curves inward, causing reflected light rays to come together. Depending on how far an object is from the mirror, its image can appear larger, smaller, upright or upside down.
Watch the swinging pendulum and its reflection. As the pendulum moves, the curved mirror changes where its image appears, creating a surprising sense of motion and depth.
Swing the pendulum, then watch its image in the mirror. Find out when it becomes larger or smaller, upright or upside down as the pedulum moves closer to and farther from the mirror.
Additional Information
Concave mirrors focus light to a point called the focal point — step past it and your reflection flips upside down.
Dentists, makeup mirrors, and car headlights all use the same curved-mirror trick to concentrate light or magnify an image.
A large enough concave mirror can focus the Sun’s rays hot enough to light a fire, no batteries required.