light
10 questions tagged light — spanning every one of the seven Ws.
Why are moths attracted to light?
Recent research suggests moths are not drawn to light itself but instinctively turn their backs toward it, which traps them.
How Does a Lighthouse Beam Reach So Far?
Lighthouses use a Fresnel lens, a set of concentric glass prisms that gathers light from a lamp and focuses it into a powerful narrow beam.
Why do some icebergs look blue?
Blue icebergs are made of dense, bubble-free glacial ice that absorbs red light, so mostly blue light is scattered back to our eyes.
What is a mirage?
A mirage is a real optical effect caused when light bends as it passes through layers of air at different temperatures, making distant objects appear displaced.
How long does sunlight take to reach Earth?
Sunlight takes about 8 minutes and 20 seconds to reach Earth, travelling roughly 150 million kilometres at the speed of light.
How do glow sticks glow?
Glow sticks glow through chemiluminescence: bending the stick breaks an inner vial, mixing chemicals whose reaction gives off light without heat.
Why do fireworks make different colors?
Different metal salts produce different colors when heated. The heat excites electrons, and each element emits its own characteristic light.
When was the first successful measurement of the speed of light made?
In 1676, Ole Rømer made the first convincing measurement from observations of Jupiter’s moon Io. He showed light travels at a finite speed.
Which fundamental force is responsible for light being able to travel through space?
Electromagnetism is responsible for light. Light itself is a stream of photons, the force carriers of the electromagnetic field.
Why do objects appear black when they absorb most light?
An object looks black when it reflects very little visible light back to your eyes. The absorbed light’s energy is usually converted into heat.