Light as Energy Creating a Change

Electromagnetic Energy Travels As Waves Of

Different Wavelengths

wavewavewavewavewavewavewavewavewavewavewavewavewave

wavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewavewave

Visible Light is part of the Electromagnetic Spectrum

Electromagnetic energy travels as transverse waves

Vocabulary to know includes:

Wavelength

Frequency

Cycle

One very important idea to know is:

The shorter the wavelength, the greater the overall energy delivered by the wave (due to a higher frequency)

The wavelength is the distance from crest to crest

One Wavelength: Crest to Crest

Time 0 sec Time 1 sec Time 2 sec

The shorter the wavelength the greater the amount of energy absorbed / exhibited, over a

specified amount of timeOne Wavelength: Crest to Crest: But smaller

Time 1 secTime 0 sec Time 2 sec Time 3 sec

The shorter the wavelength, the higher the frequency and the greater the number of cycles per 1 second, and the greater the energy of the wave can deliver! 0 sec 1 sec

Wavelengths of Visible Light http://www.windows2universe.org/sun/spectrum/multispectral_sun_overview.html

Compare the wavelengths of light, with which we worked, in our lab.

Check out the size of the wavelengths of

blue & violet light ….

…and now, check out the size of the wavelengths of red and green light.

For a metaphor to help us visualize why shorter wavelengths deliver more

energy, over time (like 1 second), think of

“rapid vs. slow” punches.

Check out this physical trainer’s video: http://www.youtube.com/watch?v=B8CTIXtnZMs

Check out this boxer hitting a target:http://www.youtube.com/watch?v=r9REsu3Y6eU

Now, transparent glass slides deal with color in a special way …

• In the case of blue glass, only blue light passed through.

• In the case of green glass, only green light got to the chemicals.

• In the case of red glass, only red light gets through to the paper.

• In the case of clear glass, all light, blue, red, and green pass through.

It takes energy to break the bond between silver and chloride in AgCl Breaking the bond produces the tiny grains of silver metal.

AgCl Ag and Cl

When there is enough energy associated with it, so wavelengths of light can cause the decomposition to occur. Obviously clear glass let all the light through (as though there were no glass at all). And because of this, silver formed under the clear glass. Which wavelength of light is really responsible for the production of the

silver?

Results

Ultraviolet LightNow, what if I told you that blue light is very, very similar to Ultraviolet light…?

UV Light is not visible to humans, because its wavelengths are just a bit too small for us to detect with our eyes.

Ultraviolet light is just a touch more powerful than visible blue light, because its wavelengths are shorter than blue light’s.

UV light is responsible for tanning!

A “tan” is an increase in the melanin concentration of the skin. Melanin is a pigment protein.

So, is light a form of energy? Can light create a change?

Now, when we’re ready for lesson #2 on color,

check out:Bill Nye: The Science Guy

http://www.youtube.com/watch?v=perm6XY-knE