Light is the result of electrons moving between defined energy levels in an atom
Atom
An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Atoms are extremely small; typical sizes are around 100 picometers (1×10⁻¹⁰ m, a ten-millionth of a millim…
Is led better than fluorescent?
Yes, LED shop lights are better than fluorescent lights. LED lights benefits outweigh those of their fluorescent counterparts. As such, it would be advisable to get LED lights for your garage instead of fluorescent ones. From LED lights being omni-directional and not wasting anything to them consuming less power and being more durable, the ...
How is light produced in nature?
Natural light is produced by natural processes, such as the sun and stars. By contrast, man-made devices, such as flashlights and light bulbs, emit artificial light. All forms of light require the release of energy, and in the natural world, this includes explosions, fires and similar phenomenon.
Is light made of atoms?
Light is not made out of atoms or anything like them. Electromagnetic waves are themselves a basic ingredient of our world. It's the light itself which enters our eyes. It is absorbed by special molecules which change their chemical configuration as a result of that absorbed energy.
Where does light energy come from?
The sun and other stars produce huge amounts of heat and light through fusion and are the source of most visible light in the universe. Other reactions that produce light are combustion and chemoluminescence. The basic unit of light is called a photon and can act as both a particle and a wave. Photons are produced when a reaction causes an electron to move from a higher nuclear orbital to a lower one, releasing energy in the process.
What is transmission of light?
Transmission of light is the moving of electromagnetic waves (whether visible light, radio waves, ultraviolet, etc.) through a material. This transmission can be reduced, or stopped, when light is reflected off the surface or absorbed by the molecules in the material. If you shine a light at 90 degrees to the surface of a medium, ...
What is the transmittance of a material?
The transmittance of a material is the proportion of the incident (approaching) light that moves all the way through to the other side. For example, let's say you're shining a flashlight on a semi-transparent glass ...
How much transmittance does a glass block have?
So you could say that the glass block has a transmittance of 20%. The transmittance of a material depends on its thickness, but it also depends on the type of light (or electromagnetic waves) you are using. A material might have a different transmittance for visible light than it does for infrared, or X-rays.
What is refracted light?
But, if you shine it at an angle, there's another term people might use. Refracted light is light that bends as it moves through a surface. When a ray of light approaches a new medium at an angle, it will bend. The direction it bends depends on whether the new medium is denser or less dense than the first one.
What is the term for light waves moving through material?
Another thing it can do is move through the material, and depending on exactly how it does this, we might call it transmission, refraction, or absorption. We will discuss each in more detail in this lesson, but transmission of light is when light waves move all the way through a material without being absorbed.
What is the difference between diffuse and specular reflection?
Reflection is when light bounces off of a surface. Specular reflection is when light reflects off of a shiny surface like a mirror. Diffuse reflection , however, is when light illuminates a dull object. Another thing it can do is move through the material, and depending on exactly how it does this, we might call it transmission, refraction, ...
How much light is absorbed by a glass block?
The first thing that happens is that 30% of that light is reflected off the outer surface of the glass. This leaves you with 70% to continue through the glass block. Another 50% of the light is absorbed by the molecules inside the glass block itself. That leaves you with 20% that emerges from the opposite side. So you could say that the glass block has a transmittance of 20%.
Where does light come from?
Photo: Arc welding gives off light when metals are melted by an electric current. The atoms are getting quite excited here! Picture by Martin Wright, courtesy of US Navy.
What does it mean when you can't see your face?
If you can see your face in something, it's specular reflection; if you can't see your face, it's diffuse reflection. Polish up a teaspoon and you can see your face quite clearly. But if the spoon is dirty, all the bits of dirt and dust are scattering light in all directions and your face disappears.
Why does light travel?
When light travels between two places (from the Sun to the Earth or from a flashlight to the sidewalk in front of you on a dark night), energy makes a journey between those two points . The energy travels in the form of waves (similar to the waves on the sea but about 100 million times smaller)—a vibrating pattern of electricity and magnetism that we call electromagnetic energy. If our eyes could see electricity and magnetism, we might see each ray of light as a wave of electricity vibrating in one direction and a wave of magnetism vibrating at right angles to it. These two waves would travel in step and at the speed of light.
Why can't we see things?
The most obvious thing about light is that it will reflect off things. The only reason we can see the things around us is that light, either from the Sun or from something like an electric lamp here on Earth , reflects off them into our eyes. Cut off the source of the light or stop it from reaching your eyes and those objects disappear. They don't cease to exist, but you can no longer see them.
How many segments are there in the James Webb space telescope?
In fact, it's six segments of the huge mirror from the James Webb Space Telescope. Picture by courtesy of NASA. Reflection can happen in two quite different ways. If you have a smooth, highly polished surface and you shine a narrow beam of light at it, you get a narrow beam of light reflected back off it.
What is the name of the energy that travels outwards?
Picture: Light energy likes to travel outwards! Most natural light floods into our world from the Sun, shown here in a dramatic closeup, emitting a blast of radiation called a solar flare. Photo courtesy of NASA Solar Dynamics Observatory (SDO) .
How long does it take for light to reach Earth?
Light arrives on our planet after a speedy trip from the Sun, 149 million km (93 million miles away). Light travels at 186,000 miles (300,000 km) per second, so the light you're seeing now was still tucked away in the Sun about eight minutes ago. Put it another way, light takes roughly twice as long to get from the Sun to Earth as it does to make a cup of coffee!
How many lightning bolts are in a flash?
Credit: NASA. Scientists have learned some facts about lightning from pictures. Some lightning flashes are made up of as many as 25 or more lightning bolts (strokes). They move so fast that your eyes only see one flash!
What happens when cold air and warm air meet?
You need cold air and warm air. When they meet, the warm air goes up. It makes thunderstorm clouds! The cold air has ice crystals. The warm air has water droplets. During the storm, the droplets and crystals bump together and move apart in the air. This rubbing makes static electrical charges in the clouds.
What happens when the charge at the bottom gets strong enough?
When the charge at the bottom gets strong enough, the cloud lets out energy. Image above: Look at a battery and find the plus end and the minus end. Credit: NASA. The energy goes through the air. It goes to a place that has the opposite charge. This lightning bolt of energy that is let out is called a leader stroke.
How far can lightning travel?
If you are swimming, get out of the water. Get out as soon as you see a storm coming. The storm may seem far away, but lightning can travel over 20 miles! During a thunderstorm, shut off or unplug all electrical items. Do not use the phone.
How do you know if you have a lightning strike?
How will you know if a lightning strike is near you? You will feel the hair on your head or body start to stand up. If this happens, go to a safe place. Go quickly! If there is no safe place near, get as close to the ground as you can.
Can lightning go from the cloud to the ground?
It can go from the cloud to the ground. Or, a leader stroke can go from the cloud to another cloud. No one is sure why lightning bolts follow a zigzag path as they move. The main bolt or stroke will go back up to the cloud. It will make a flash of lightning. It will also heat the air. The air will spread quickly.
Did Ben Franklin fly a kite during a thunderstorm?
You have heard of Ben Franklin. Did you know he flew a kite during a thunderstorm? He wanted to prove that lightning is a form of electricity. We know now that flying a kite in a storm is not safe. But, Ben was right. Lightning is a form of electricity. How does this "electricity" form?
How to fall asleep faster?
That should help you fall asleep more easily. If you are getting sleepy too early in the evening, you can go into a well-lit area to reduce the sleepiness. (However, if you are sleep deprived or fighting an infection, go to sleep early and catch up on needed sleep.) Bright morning light will shift the time for sleep earlier, ...
How does light affect the circadian rhythm?
Effects of Light on Circadian Rhythms. The light/dark cycle of the sun has a powerful effect on the circadian clock, sleep, and alertness. If you understand these effects, you can manipulate light exposure to help yourself sleep better at night and be more alert during the day. Keep in mind your circadian clock uses light ...
What does the circadian clock do?
Keep in mind your circadian clock uses light and dark signals to predict what to do in the future: when to prepare you to be active and when to prepare you to sleep.
What to do if you have to get up in the middle of the night?
If you have to get up in the middle of the night, keep light level very dim.
Does bright light make you sleepy?
Bright morning light will shift the time for sleep earlier, so you will tend to get sleepy and fall asleep earlier in the evening and will wake up earlier in the morning.
What are the Northern Lights and the Southern Lights?
Michael S. Quinton/National Geographic/ Getty Images. The aurora borealis (the Northern Lights) and the aurora australis (the Southern Lights) have always fascinated mankind, and people even travel thousands of miles just to see the brilliant light shows in the earth's atmosphere. The auroras, both surrounding the north magnetic pole (aurora ...
How fast do auroras travel?
Solar winds stream away from the sun at speeds of about 1 million miles per hour. When they reach the earth, some 40 hours ...
Where do auroras occur?
The auroras generally occur along the "auroral ovals," which center on the magnetic poles (not the geographic poles) and roughly correspond with the Arctic and Antarctic circles. There are times, though, when the lights are farther south, usually when there are a lot of sunspots. Sunspot activity follows an 11-year cycle.
What color is the Aurora?
Advertisement. Green - oxygen, up to 150 miles in altitude. Red - oxygen, above 150 miles in altitude. Blue - nitrogen, up to 60 miles in altitude. Purple/violet - nitrogen, above 60 miles in altitude.