COMT 3912 Fundamentals The Metric System What is a “Wave” Calculations in “Decibels”
COMT 3913 The Metric System Based on MKS - Meters, Kilograms, Seconds 1 m is about 3 feet 1 kg is about 2.2 pounds
COMT 3914 “Scientific” Notation Large and small numbers are written as a number “around” 1, multiplied by ten raised to the proper power –41,400 = 4.14x10 4 –1,000,000,000,000 = 1x10 12 –0.0000543 = 5.43x10 -5
COMT 3915 Try It 9845 768000000 0.012 0.3 0.0000000004
COMT 39115 Measurements Amplitude (A) Wavelength ( ) in meters (with prefix) Number of cycles per second is frequency (f) In 1/sec = Hz
COMT 39116 Types of Waves Sound - pressure disturbance in a medium (air, water, etc.) Surface - disturbance in the “normal” position of the surface Electromagnetic - alternating electric and magnetic disturbances in a medium or in a vacuum.
COMT 39117 For all waves: The speed of the wave is equal to the product of the wavelength and the frequency.
COMT 39118 Some Examples Speed of light: 3x10 8 m/s Find the wavelength for each case –AC Current: 60Hz –FM Radio: 90MHz –Ka Band Satellite: 20GHz –Ultraviolet Light: 10 15 Hz The speed of the wave is equal to the product of the wavelength and the frequency.
COMT 39119 Some Examples Speed of light: 3x10 8 m/s Find the wavelength for each case –AC Current: 60Hz = 5000km –FM Radio: 90MHz = 3.33m –Ka Band Satellite: 20GHz = 15mm –Ultraviolet Light: 10 15 Hz = 3x10 -7 m The speed of the wave is equal to the product of the wavelength and the frequency.
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