If red light has a lower photon energy than blue or purple light, it must also have a longer wavelength and a smaller frequency. Indeed, these factors are what differentiate all colors of light from one another. The following videos can help you elucidate and demonstrate the basic concepts underlying the discoveries students made as they explored.
Video 1: Light and Color Part 3. This excerpt from the Light and Color episode of the EveryDay Science show is a brief exploration of some of the wave properties of light. We work with a diffraction grating all about constructive and destructive interference!
Video 2: Light and Color Part A variation on the Writing With Light activity we looked at in the Explore section, this one with glow-in-the dark phosphorescent basketballs and red, green, and violet lasers.
We use it to give a brief introduction to the photon model of light, and make a connection between photon energy and light color. Video 1: Light and Color Part 5. We know that the wave nature of light allows it to undergo constructive and destructive interference, like any wave.
Video 2: The Greenhouse Effect. In the Engage section we saw a video taken in the near-IR instead of in the visible light. A greenhouse gas is one whose constituent molecules, due to their unequal intramolecular sharing of charges, interact with thermal radiation.
If a more-electronegative atom is covalently bonded to a less-electronegative atom, the bonding electrons will spend more time closer to the more-electronegative atom.
We say that the more-electronegative atom has a partial negative charge, the less-electronegative atom, a partial positive charge. Examples of molecules with this sort of bonding arrangement include water vapor and carbon dioxide — both of which are greenhouse gases. The electric field of thermal radiation pushes on the partially-charged atoms within each greenhouse gas molecule, causing the molecule to twist or bend or vibrate, and thus increasing its energy.
The molecule has absorbed the energy carried by the thermal radiation, but it would be favorable for the molecule to return to its energetic ground state. When it does so, it emits thermal radiation. This is the basic physical reason: 1 that we can see greenhouse gases, but not gases whose molecules share charges equally such as diatomic nitrogen and oxygen on the thermal camera, 2 that the earth is warm enough to support life as we know it, and 3 that greenhouse gases are part of the climate change conversation.
Energy from the sun is carried by electromagnetic waves primarily in the visible spectrum but with a mix of IR and UV to the earth. The earth absorbs this energy, then emits it as thermal radiation. If this outgoing radiation is absorbed by a greenhouse gas molecule in the atmosphere, the direction in which the molecule re-emits it is random.
This has big implications for global climate. Video 3: Light and Color Part With the advent of solar energy technology, humans can now capture light energy as well, and convert it into electrical energy.
Tests and quizzes are one option, but there are many others. This one is up to you — what works best for you and your students? We, for example, have had good results with turning the tables and letting the students make a video at this stage.
Video 1: Polarization of the Sky To get things off the ground, a surprising practical application of the wave nature of light. Video 3: Flashy Grape We continue our journey down the electromagnetic spectrum with a video about microwaves.
Explore In the explore segment, students get to experience firsthand the principles we hope to teach them. Video 4: Writing with Light The last two videos considered primarily the wave nature of visible light. Video 1: Light and Color Part 3 This excerpt from the Light and Color episode of the EveryDay Science show is a brief exploration of some of the wave properties of light. Video 2: Light and Color Part 15 A variation on the Writing With Light activity we looked at in the Explore section, this one with glow-in-the dark phosphorescent basketballs and red, green, and violet lasers.
Video 1: Light and Color Part 5 We know that the wave nature of light allows it to undergo constructive and destructive interference, like any wave. This energy can be described by frequency, wavelength, or energy. All three are related mathematically such that if you know one, you can calculate the other two. Radio and microwaves are usually described in terms of frequency Hertz , infrared and visible light in terms of wavelength meters , and x-rays and gamma rays in terms of energy electron volts.
This is a scientific convention that allows the convenient use of units that have numbers that are neither too large nor too small. The number of crests that pass a given point within one second is described as the frequency of the wave. One wave—or cycle—per second is called a Hertz Hz , after Heinrich Hertz who established the existence of radio waves.
A wave with two cycles that pass a point in one second has a frequency of 2 Hz. Electromagnetic waves have crests and troughs similar to those of ocean waves. The distance between crests is the wavelength. The shortest wavelengths are just fractions of the size of an atom, while the longest wavelengths scientists currently study can be larger than the diameter of our planet! An electromagnetic wave can also be described in terms of its energy—in units of measure called electron volts eV.
An electron volt is the amount of kinetic energy needed to move an electron through one volt potential. Moving along the spectrum from long to short wavelengths, energy increases as the wavelength shortens. Consider a jump rope with its ends being pulled up and down. More energy is needed to make the rope have more waves. Top of Page Next: Wave Behaviors. Anatomy of an Electromagnetic Wave. Retrieved [insert date - e. Science Mission Directorate. National Aeronautics and Space Administration.
Anatomy of an Electromagnetic Wave Energy, a measure of the ability to do work, comes in many forms and can transform from one type to another. Classical waves transfer energy without transporting matter through the medium. Waves in a pond do not carry the water molecules from place to place; rather the wave's energy travels through the water, leaving the water molecules in place, much like a bug bobbing on top of ripples in water.
When a balloon is rubbed against a head of hair, astatic electric charge is created causing their individual hairs to repel one another. Credit: Ginger Butcher. Electromagnetic Spectrum Series Series Homepage. When white light shines through a prism or through water vapor like this rainbow, the white light is broken apart into the colors of the visible light spectrum.
Cones in our eyes are receivers for these tiny visible light waves. The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us. The color of an object that we see is the color of light reflected. All other colors are absorbed. Light bulbs are another source of visible light waves.
0コメント