Watch Hewitt-Drew-it! Good Vibrations and Waves #82 and complete #1 through #13 below.

1. A vibration is a __________ wiggle in time. A periodic wiggle in both space and time is a ___________. A wave extends from one place to another.

2. Light and _________ are both vibrations that propogate throughout space as ________. Sound is a __________ wave. Sound needs a _____________ to propagate through. However produced, sound cannot travel in a ____________, but light can, which is evident when light propagates through the vacuum between the sun and earth.

3. Light is a vibration of __________ and magnetic fields. An electromagnetic wave of pure ____________. Unlike sound, light does not need a _____________ to propagate.

The source of all waves is something that is ____________.

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4. The shape of the waves shown above approximate a __________ curve. The high points are called _________ and the low points ___________ as in a water wave. ___________ refers to the distance from the ____________ to the crest or __________ of the wave. Wavelength is the distance from the top of one crest to the top of the next crest. Wavelength is expressed with the Greek letter for length, __________. Wavelengths of waves at the beach are measured in _________, the wavelengths of ripples in a pond are measured in ______________ , and the wavelengths of light are measured in _________________ of a meter or ________ meters.

5. How frequently a vibration occurs is described by its ________________. Frequency specifies the number of to and fro vibrations occuring in a given time, usually _________. A complete to and fro oscillation is one ____________. If it occurs in one second, the frequency is one vibration per one second or one ________. The unit of frequency is called the _________ after Mr. __________ who demonstrated _________ waves in the year ___________. One vibration per second is _________, two vibrations per second is _____________ and so on. Higher frequencies are measured in __________, that is thousands of hertz, still higher frequencies in __________, that is ___________ of hertz and yet still higher frequencies in giga hertz or ___________ of hertz.

6. A radio station that broadcasts at 101.7 MHz on the FM dial transmits ________ waves having a frequency of _____________________ Hz the same frequency at which electrons are forced to vibrate in the antennae of the radio station’s transmitting tower. Electrons are made to slosh up and down at ___________________ times each second.

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7. The source of all waves is something that _____________. The frequency of the vibrating ________ and the frequency of the wave it produces are the same.

8. The period of a wave is the time for ____________ complete vibration. If an object’s frequency is known, its period is the reciprocal. If, for example, the frequency of vibration is 2 Hertz, the time needed to complete one vibration, the period of vibration, is ______ second. If the vibration frequency is 3 Hertz then the period of vibration is ________ second. The period and frequency are ___________ of each other.

Τ = 1 f = 1

9. The speed of a wave, like any speed, is defined as the distance divided by _________. Let the distance be one wavelength, then the time is the ___________.

SPEED = dis tancetime

=Τ= λ ____

10. This relationship holds true for all kinds of waves, whether they are waves on a ____________string, ___________ waves, or ____________ waves.

12. What is the speed of a water wave that oscillates up and down 3 times a second and the distance between wave crests is 1 meter?

13. What is the wavelength of a sound wave whose frequency is 34 Hz? The speed of sound is 340 m/s.

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