Science for Kids: Things you didn't know about Light

What is "Light"

Light is a type of energy. It is a form of electromagnetic radiation of a wavelength which can

be detected by the human eye. In physics, the term light sometimes refers to electromagnetic

radiation of any wavelength, whether visible or not. Light exists in tiny packets called photons.

It shows properties of both waves and particles. The study of light, known as optics, is an important

research area in modern physics.

Things you didn't know about Light

1. Light didn't travel freely for half a million years, that's how long after the big bang the universe took to expand "enough" to allow photons (light particles) to travel freely in space.

2. Those photons are still running loose, detectable as the cosmic microwave background, a microwave glow from all part of the sky.

3. Light moves along at full "light speed" (186,282.4 miles per second) only in a vacume space where there is nothing to hold it. In the dense matrix of a diamond, it slows to just 77,500 miles per second.

4. Diamonds are like a prison to light, any entering photons quickly gets bogged down. It takes a lot of pinging back and forth in a thick jungle of carbon atoms to find an exit. This action is what gives diamonds their dazzling sparkle.

5. Eyeglasses can correct vision because light changes speed when it passes from air to a glass or plastic lense; this causes the rays of light to bend.

6. "Plato" said that we see by shooting light rays from our eyes.

7. The greek philosopher was not completely wrong. Like most living things, humans are bio-luminescent, yes..."Humans glow in the dark". We are brightest during the afternoon, around our lips and cheeks. The cause maybe chemical reaction involving molecular fragments known as "free radicals".

8. Bioluminescent phenomenon is the largest source of light in the oceans; 90 percent of all creatures who live below about 1,500 feet are luminous.

9. Worldwar II aviators used to spot ships by the bioluminescence phenomenon. In 1954 Jim lovell(later the pilot of Apollo13) used this trick to find his darkened aircraft carrier.

10. Incandescent bulbs convert only 10 percent of the energy they draw into light, which is why Europe will outlaw them by 2012. Most of the electricity turns into unwanted heat.

11. In the confined space of an easy-bake oven. a 100-watt bulb can create a temperature of 325 degrees fahrenheit.

12. Light has no mass, but it does have momentum. Later this year the "planetary society" will launch LightSail-1, attempting to capture the pressure of sunlight the way a boat's sail gathers the wind.

13. Laser beams bounced off mirrors left behind by Apollo astronauts shows that the moon is moving 1.5 inches farther from earth each year.

14. Visible light makes up less than one ten-billionth of the electromagnetic spectrum, which stretches from radio waves to gamma rays.

15. Goldfish can see infrared radiation that is invisible to us. Bees, birds, and lizards have eyes that pick up ultraviolet.

16. "Photography" means "writing with ligh". English astronomer John Herschel, whose father discovered infrared, coined the term.

17. Auroras light up the night sky when solar wind particles excite atoms in the upper atmosphere. Oxygen mostly shines green; nitrogen glows in blue and red.

Changes in human bioluminescence over time Photograph: PLoS ONE/Public Domain.Amazing pictures of "glittering" human bodies have been released by Japanese scientists who have captured the first ever images of human "bio-luminescence".

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.The electromagnetic spectrum extends from low frequencies used for modern radio to gamma radiation at the short-wavelength end, covering wavelengths from thousands of kilometers down to a fraction of the size of an atom. The long wavelength limit is the size of the universe itself, while it is thought that the short wavelength limit is in the vicinity of the Planck length, although in principle the spectrum is infinite and continuous. Although some radiations are marked as "N" for "no" in the diagram, some waves do in fact penetrate the atmosphere, although extremely minimally compared to the other radiations.

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