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Unit 6: Light Physics B Anatomy of a waveβ¦ Waves β’ https://www.youtube.com/watch?v=2awbKQ2DLRE Determine: Ξ», A, T, f, v, k, and Ο Period (T): how long it takes for a single wave to pass a single point. seconds Frequency (f): number of waves that pass a given point in a time period of one second. Hertz (Hz) = 1/s Q. What is the period of a 60 Hz wave traveling at 3.0 x 108 m/s? π£ = πΞ» This equation gives us the speed of a wave, given the information we know about a waveβ¦.. This will be VERY important later on. Q. If the speed is a constant (depending on the wave), what does this tell us about the relationship between the frequency and the wavelength? k (wave number) 2π π= Ξ» The distance between consecutive maxima. Ο (angular frequency) Ο = 2ππ = π£π Angular frequency = 2Ο*frequency or speed of wave * wave number Ο = [rad/sec] http://www.animatedscience.co.uk/blog/wpcontent/uploads/focus_waves/auxcircle.html Ξ¦ (Phase Shift) is the fraction of the wave cycle which has elapsed relative to the origin. In phase Out of Phase Together we getβ¦. The mathematical description of a wave! π¦ π₯, π‘ = π΄πππ (ππ₯ β Οπ‘ + Ο) A sinusoidal wave moving in the +x direction But, we will work primarily with the simpler version: π¦ π‘ = π΄πππ π€π‘ Wave traveling left or right? π¦ π₯, π‘ = βπ΄πππ ππ₯ + π€π‘ Incident wave traveling to the left π¦ π₯, π‘ = π΄πππ ππ₯ β π€π‘ Incident wave traveling to the right Sine and Cosine Waves Sine and Cosine Waves continuedβ¦ β’ To determine nodes, all you need to do is know about the individual types of waves, sine and cosine. β’ For sine, the function is 0, when the inside of the function is: 0, Ο, 2Ο, etcβ¦ β’ For cosine, the function is 0, when the inside of the function is: π 3π , , etcβ¦ 2 2 Practice http://www.cabrillo.edu/~jmccullough/Physics/Waves_Sound.html What does the full π¦ π₯, π‘ = π΄πππ (ππ₯ β Οπ‘ + Ο) equation look like? So, why do we need to know this? E π₯, π‘ = πΈπ πππ (ππ₯ β Οπ‘) Superposition Bell Work: What do EM waves look like? The EM Wave http://www.cabrillo.edu/~jmccullough/Applets/Flash/Optics/EMWave.swf Covered β’ Wave Characteristics β’ The Wave Equation β’ Interference & Superposition β’ Causes of EM Waves β’ Electromagnetic Spectrum β’ Characteristics of Particular EM Waves Today β’ The E & M in EM Wave β’ Speed of Light β’ Energy of EM Waves β’ Doppler Shift Oscillating Electric & Magnetic Fields πΈ = ππ΅ Where, c is the speed of light! π = 3 × 108 m/s Q. Soβ¦β¦. What causes this to even happen? Oscillating CHARGED Particles http://phet.colorado.edu/en/simulation/radio-waves The EM Spectrum Because of the large variation in EM waves (massive differences in wavelengths and frequencies), we separate them into categoriesβ¦ Radio Microwave Infrared Visible Ultra Violet X-Ray Gamma The Speed of Light π = 3 × 108 m/s Measuring the Speed of Light https://www.youtube.com/watch?v=DMKE5YGLnmc Breaking the Speed of Light https://www.youtube.com/watch?v=EPsG8td7C5k Speed of an EM Wave π = Ξ»π Speed of Light = wave length * frequency Energy of an EM Wave πΈ = βπ Energy = Constant * frequency The Doppler Effect http://www.cabrillo.edu/~jmccullough/Applets/Flash/Fluids,%20Oscilla tions%20and%20Waves/DopplerWaveFronts.swf Applications? Photonic Boom?
