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Copy of Light Energy

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carolyn milford

on 14 October 2015

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Transcript of Copy of Light Energy

Light has much in common with sound. Light is a form of energy and travels in waves. Light helps us see colors and shapes of objects. A bonfire, a street light, and a candle are a few examples of sources of light.

Do you know any other sources of light?
What is light?
How does light create shadows?
Light travels in
straight lines called rays
that move outward from the light source. Shadows occur when something blocks the lights' path.

Think about it . . . How does your shadow change throughout the day?
Light Waves We See
The light that we can see makes up only a little bit of the universe's light energy. Scientists call all forms of light energy

. Visible light, the light we can see, is the most familiar form of electromagnetic waves.
Electromagnetic Waves We Cannot See
Most electromagnetic waves are not visible to the human eye. For example, radio waves, microwaves, and infrared waves are invisible because their wavelengths are too long for the human eye to see. On the other hand, Ultraviolet waves, X rays, and gamma rays are high-energy waves. These rays are invisible because their wave lengths are too short.
The Sun
The sun gives us a constant supply of light energy and is the most important supply of light energy for everything on Earth. The sun keeps us warm and makes our day brighter. Plants convert sunlight into food and without plants humans and animals would have a difficult time surviving.
Some animals give off light known as
. Bioluminescence happens when a chemical reaction goes on inside the animal's body. Bioluminescence can help these animals see better and find their way around. Fireflies and some types of jellyfish are examples of animals that give off bioluminescence.
Light energy travels through space as waves. Light energy waves have wavelengths and frequencies like many other types of energy.
is the distance from the top of one wave to the next.
is the number of times the wave goes up and down per second.
Light Waves We See (cont.)
Light Waves We See (cont.)
The human eye can see only the wavelengths and frequencies of the colors in the visible spectrum. White light, such as light from the sun, is actually a blend of colors in a rainbow. Sunlight that passes through raindrops is split into their individual colors. This is why rainbows can be seen on rainy days!
Not these waves!
Light Waves We See (cont.)
Visible Spectrum
Light Waves
The colors in a rainbow always show up in the same order (Red, Orange, Yellow, Green, Blue, Indigo, Violet) because of their wavelength and frequency. As you move from left to right on the spectrum, wavelength decreases and frequency increases. So, the red light has the longest wavelength and the lowest frequency. Violet has the shortest wavelength and the highest frequency.
X rays
Electromagnetic Waves We Cannot See (cont.)
Scientific Equipment
Scientists use special equipment to study invisible waves. These invisible waves behave in the same way as visible waves. All electromagnetic waves travel at the same speed and carry energy. This energy can be absorbed by an object and changed to another form of energy, such as heat.
Electromagnetic Waves We Cannot See (cont.)
Large amounts of high-energy waves can harm living cells. For example, ultraviolet waves from the Sun can damage the eyes or cause sunburn or cancer. In smaller amounts, however, these waves can be helpful. Microwaves can heat up food and X rays show doctors things such as broken bones.
Vests such as these are used to protect your body from harmful X rays.
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The End
Full transcript