PHY183-Lecture53

# PHY183-Lecture53 - Few points ! Final Exam date: Thurs. May...

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April 27, 2006 Physics for Scientists&Engineers 1 1 Physics for Scientists & Engineers 1 Spring Semester 2006 Lecture 53 April 27, 2006 Physics for Scientists&Engineers 1 2 Few points ! Final Exam date: Thurs. May 4, 8-10 pm E100 VMC (Veterinary Medical Center) Bldg. ! Make-up Final Exam date: (for students with good excuse) Tues. May 2, 3-5 pm 1420 BPS Bldg. Please contact Profs. Schmidt or Yuan ! Clicker points (thru April 18) posted on Lon-Capa Maximum points so far: 146 Scores out of ! maximum = 73 ! Practice final exam posted in DOCS in Lon-Capa April 27, 2006 Physics for Scientists&Engineers 1 3 Review: Wave Power and Intensity Review: Wave Power and Intensity ! Definition of intensity = power radiated per cross sectional area ! Result: ! No damping => wave power radiating outward is independent of distance from source ! 3d: I = P A ! I = 1 2 ! v " 2 A ( r ) 2 A ! = 4 r 2 # r 2 A ( r ) 2 = constant # A ( r ) \$ 1/ r April 27, 2006 Physics for Scientists&Engineers 1 4 Radial Dependence of Intensity Radial Dependence of Intensity ! Spherical wave in 3d ! => Intensity as a function of r: ! Ratio: A ( r ) ! r I ! 1 r 2 I 1 I 2 = r 2 r 1 ! " # \$ % & 2

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April 27, 2006 Physics for Scientists&Engineers 1 5 Superposition Principle Superposition Principle ! Wave equation is linear and homogeneous => function y only appears in first power in each term in the equation ! If you have two solutions to the wave equation, then any linear combination of the two is also a solution ! Superposition principle: “Two or more wave solutions can be added to result in another wave solution” y ( x , t ) = ay 1 ( x , t ) + by 2 ( x , t ) y ( x , t ) = y 1 ( x , t ) + y 2 ( x , t ) April 27, 2006 Physics for Scientists&Engineers 1 6 Example: Superposition !
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## PHY183-Lecture53 - Few points ! Final Exam date: Thurs. May...

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