All light has both particle-like and wave-like properties. How an instrument is designed to sense the light influences which of these properties are observed. An instrument that diffracts light into a spectrum for analysis is an example of observing the wave-like property of light. The particle-like nature of light is observed by detectors used in digital cameras—individual photons liberate electrons that are used for the detection and storage of the image data.
One of the physical properties of light is that it can be polarized. Polarization is a measurement of the electromagnetic field's alignment. In the figure above, the electric field in red is vertically polarized. Think of a throwing a Frisbee at a picket fence. In one orientation it will pass through, in another it will be rejected.
This is similar to how sunglasses are able to eliminate glare by absorbing the polarized portion of the light. The terms light, electromagnetic waves, and radiation all refer to the same physical phenomenon: 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.
I have heard that humans have a wavelength. Is this true?
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.
I have heard that humans have a wavelength. Is this true?
More energy is needed to make the rope have more waves. Anatomy of an Electromagnetic Wave. Retrieved [insert date - e. National Aeronautics and Space Administration. Tour of the Electromagnetic Spectrum.
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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.
Note that the speed of sound does not mean the speed of the air molecules as they move back and forth. The air molecules are moving with the speed, but by the speed of sound, we mean the speed of the disturbance as it moves through the air molecules.
We call sound a longitudinal wave because the wave is traveling parallel to the line traced out by the oscillations of the medium. The other type of wave is a transverse wave. Transverse waves happen when the wave velocity points perpendicular to the oscillations of the medium.
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Waves on a string or waves on the surface of water are examples of transverse waves. If we look at a graph of the air displacement versus position of the air, we can see that as the wave travels the shape of this wave travels to the right. So, the speed of a sound wave can be found by finding the speed of the peaks or the speed of the valleys or the speed of any single point on the wave shape.
To figure out a formula for the velocity of a sound wave, let's look closely at what's happening here. Watch one of the air molecules. It takes one period for this molecule to move back and forth through a full cycle. During this time, the wave shape has moved forward one complete wavelength. This is because the wave has to overlap with its initial shape after one period, because the molecule has to be back where it started after one period. Now, since speed is defined to be the distance per time, the speed of a sound wave has to be the wavelength of the wave divided by the period of the wave.
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Since the wave is traveling forwards one wavelength per period, or since the frequency is defined to be one over the period, we can rewrite this formula as speed equals wavelength times frequency. This formula is accurate for all kinds of waves, not just sound waves, because a wave has to move one wavelength for every period. When looking at this equation, you might think that if you adjust the setting on your speaker and increase the frequency you'd also be increasing the speed of the sound wave, but that's not what happens.
If you increase the frequency, the wavelength will decrease by that same factor, and the speed of the sound wave will remain the same. In fact, there's nothing you can do to the speaker that would increase the speed of sound.
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So, how can we change the speed of sound?