PHY 102 1nd Edition Lecture 14 Outline of Last Lecture I. SantaOutline of Current Lecture I. WavesII. Sound WavesIII. Light WavesIV. IntensityV. InterferenceVI. DiffractionCurrent LectureI. Wavesa. T = period = time it takes to make a complete oscillationb. f = frequency = 1/T (inverse of T)i. Number of oscillations per secondii. Unit = 1/s, s-1, cps (cycle per second), rps (revolution per second)c. Wave is a disturbance in a medium that movesd. Top = crest, bottom = troughe. Wavelenght = λ = distance between two consecutive crests or troughsf. v = distance/timei. one wavelength/one period = λ/T = λfg. Transverse wave: oscillation is perpendicular to the direction of motion of waveh. Longitudinal wave: oscillation is in the same direction as wave motioni. Speed of a wave is constant regardless of λ or fII. Sound Wavesa. Speed = 340 m/sb. Frequency can be anythingi. Audible frequency = 20-20,000 Hz1. Example: ultrasound is 100,000 Hzc. LongitudinalIII. Light Wavesa. Speed = c = 300,000 km/s = 3x108 m/sb. Wavelength can be anythingi. Visible wavelength = 400-700 nm = 0.4-0.7 μm = 0.4x10-6-0.7x10-6 mThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. 0.4 = violet, 0.7 = redIV. Intensitya. Sound = loudnessb. Light = brightnessc. I is proportional to (Amplitude)2i. The higher the amplitude, the more intense the wave isV. Interferencea. Sources that produce waves in unison are called coherent sourcesb. Two coherent sources produce interferencei. Destructive regions (no wave)ii. Constructive regions (between two destructive regions)c. Criterion for two coherent sources to produce interferencei. Distance between two holes < 10 λVI. Diffractiona. One holeb. Criterion for diffraction to take placei. Size of hole (aperture) < 10 λc. λ for light = 0.5x106 m, 10 λ = 0.5x10-5 m = 0.005 mmi. A drill hole = 1 cm but you need a much smaller hole (reason why you don’t see
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