Waves

Light Waves

Visible Light Waves

Wavelength, Energy, and Frequency

(from http://csep10.phys.utk.edu/astr162/lect/light/waves.html)

The speed of light in a vacuum is commonly given the symbol c. It is a universal constant that has the value

Sound Waves

Properties of Sound

There are millions of different sounds in everyday life.  Each sound having certain characteristics that make it unique.  Think about the many sounds you hear everyday.  How you hear and describe a sound depends on the physical characteristics of the sound wave.

• Frequency and Pitch 

                Certain sounds are described as high, such as those produced by a piccolo, or low, such as those produced by a bass drum.  A description of a sound as high or low is known as the pitch of the sound.  The pitch of a sound depends on how fast the particles of a medium (the material through which a wave travels) vibrate.  So the pitch of a sound depends on the number of waves produced in a given time.

                Frequency is an especially important characteristic of sound because the ear can respond to only certain frequencies.  The normal human ear is capable of detecting from about 20 to 20,000 vibrations per second, or hertz.

Here is a helpful link for more information on sound waves:  http://www.ronkurtus.com/physcien/sound.htm

Actvities

Interactive Sound Waves

 

Frequency

In this interactive activity adapted from the University of Utah's ASPIRE Lab, investigate frequency in terms of trampoline jumps, pendulum swings, and electromagnetic waves.

 

Radio Transmission

This interactive activity from A Science Odyssey tracks the journey of a sound wave from the moment a musician sings into a microphone until his voice reaches the vibrating speakers of an AM Radio.

 

Visible light waves are the only electromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light.

Interactives

The name of this "learning tool" is called Geometric Optics. How does a lens form an image? See how light rays are refracted by a lens. Watch how the image changes when you adjust the focal length of the lens, move the object, move the lens, or move the screen.

Learn about the nature of light the way Isaac Newton learned! With this learning tool students can manipulate two simple prisms to find out what Newton discovered. the name of the tool is Newton's Prism Experiments. This "learning tool" comes to us from an elegant site for microscopy called Molecular Expressions.

The name of this "learning tool" is called Light and Shadows. Use the blue arrows in the upper right hand corner to go through the simulation. This tool has been developed by the bbc.co.uk and their Science Clips program.

In this wonderfully engaging "learning tool" students interact with the concept of light and reflection. Students use mirrors to shoot a beam of light around a virtual landscape and then answer some questions about light. This "learning tool" is called How We See Things and is brought to us by BBCi Schools.

in two different useful sets of units (eV stands for "electron volts"; electron volts and ergs are two common units of energy). Thus, these equations allow us to freely interconvert among frequency, wavelength, and energy for electromagnetic waves: specifying one also specifies the others.

Some Light Exercise

Here are some exercises illustrating the conversion among energy, wavelength, and frequency for electromagnetic waves.

The speed of light in a medium is generally less than this. Normally the term "speed of light", without further qualification, refers to the speed in a vacuum.

A wave can be characterized by its wavelength, but we can also characterize it by the frequency (how many wavelengths pass a fixed point in a given time; think of sitting on the dock---of the bay---counting the number of water waves passing in one minute) and the energy that it carries (think of a water wave knocking you over in heavy surf). For light waves the relationship among the wavelength (usually denoted by Greek "lambda"), the frequency (usually denoted by Greek "nu"), and the energy E are

where c is the speed of light and h is another universal constant called Planck's Constant that has the values

When white light shines through a prism, the white light is broken apart into the colors of the visible light spectrum. Water vapor in the atmosphere can also break apart wavelengths creating a rainbow.