Slide 1Lightning ReviewReminder (for those who don’t read syllabus)Review problem: RLC circuitSlide 5A Brief Overview of Modern PhysicsBasic ProblemsGalilean RelativityGalilean Relativity – ExampleGalilean Relativity – Example, contGalilean Relativity – Example, conclusionGalilean Relativity – LimitationsLuminiferous EtherVerifying the Luminiferous Ether1101/14/1901/14/19General Physics (PHY 2140)Lecture 23Lecture 23 Modern PhysicsRelativityThe principle of relativityThe speed of LightChapter 26http://www.physics.wayne.edu/~apetrov/PHY2140/2201/14/1901/14/19Lightning ReviewLightning ReviewLast lecture: 1.1.AC circuits and EM wavesAC circuits and EM wavesEM wavesEM wavesSpectrum of EM radiationSpectrum of EM radiationReview Problem: The phasor diagrams below represent three oscillating emfs having different amplitudes and frequencies at a certain instant of time t = 0. As t increases, each phasor rotates counterclockwise and completely determines a sinusoidal oscillation. At the instant of time shown, the magnitude of  associated with each phasor given in ascending order by diagrams 1. (a), (b), and (c). 4. (c), (a), and (b). 2. (a), (c), and (b). 5. none of the above 3. (b), (c), and (a). 6. need more information( )22L CZ R X X= + -tanL CX XRf-=1, 22C LX X fLfCpp= =( )sin 2mv V fp fD =D +3301/14/1901/14/19Reminder (for those who don’t read Reminder (for those who don’t read syllabussyllabus)) Reading Quizzes (bonus 5%):It is important for you to come to class prepared, i.e. be familiar with the material to be presented. To test your preparedness, a simple five-minute quiz, testing your qualitative familiarity with the material to be discussed in class, will be given at the beginning of some of the classes. No make-up reading quizzes will be given.There could be one today… … but then again…4401/14/1901/14/19Review problem: RLC circuitReview problem: RLC circuitIn a certain RLC circuit, the rms current is 6.0 A, the rms voltage is 240 V, and the current leads the voltage by 53°. (a) What is the total resistance of the circuit? (b) Calculate the total reactance XL – XC .5501/14/1901/14/19In a certain RLC circuit, the rms current is 6.0 A, the rms voltage is 240 V, and the current leads the voltage by 53°. (a) What is the total resistance of the circuit? (b) Calculate the total reactance XL – XC . Given:RLC circuit= -53˚VRMS = 240 VIRMS = 5.0 A Find:(a) R=?(b) XL-XC=?Recall that dissipated power is 2and cosP I R P I V f= = DNow that we know the resistance, the total reactance istan or tanL CL CX XX X RRf-= - =( )cos cos240cos 53 246.00rmsrmsVVRI IVAf� �DD� �= =� �� �� �� �� �= - = W� �� �o2cosI R I V f= D( )( )24 tan 53 32L CX X- = W - =- Wo6601/14/1901/14/19A Brief Overview of Modern PhysicsA Brief Overview of Modern Physics2020thth Century revolution Century revolution1900 Max Planck1900 Max PlanckBasic ideas leading to Quantum theoryBasic ideas leading to Quantum theory1905 Einstein1905 EinsteinSpecial Theory of RelativitySpecial Theory of Relativity2121stst Century CenturyStory is still incompleteStory is still incomplete7701/14/1901/14/19Basic ProblemsBasic ProblemsThe speed of every particle in the universe always remains The speed of every particle in the universe always remains less thanless than the speed of light the speed of lightNewtonian Mechanics is a limited theoryNewtonian Mechanics is a limited theoryIt places no upper limit on speedIt places no upper limit on speedIt is contrary to modern experimental resultsIt is contrary to modern experimental resultsNewtonian Mechanics becomes a specialized case of Newtonian Mechanics becomes a specialized case of Einstein’s Theory of Special RelativityEinstein’s Theory of Special RelativityWhen speeds are much less than the speed of lightWhen speeds are much less than the speed of light8801/14/1901/14/19Galilean RelativityGalilean RelativityChoose a Choose a frame of referenceframe of referenceNecessary to describe a physical eventNecessary to describe a physical eventAccording to Galilean Relativity, the laws of mechanics are the same According to Galilean Relativity, the laws of mechanics are the same in all inertial frames of referencein all inertial frames of referenceAn inertial frame of reference is one in which Newton’s Laws are validAn inertial frame of reference is one in which Newton’s Laws are validObjects subjected to no forces will move in straight linesObjects subjected to no forces will move in straight lines9901/14/1901/14/19Galilean Relativity – ExampleGalilean Relativity – ExampleA passenger in an airplane A passenger in an airplane throws a ball straight upthrows a ball straight upIt appears to move in a vertical It appears to move in a vertical pathpathThe law of gravity and The law of gravity and equations of motion under equations of motion under uniform acceleration are uniform acceleration are obeyedobeyed101001/14/1901/14/19Galilean Relativity – Example, contGalilean Relativity – Example, contThere is a stationary observer There is a stationary observer on the groundon the groundViews the path of the ball Views the path of the ball thrown to be a parabolathrown to be a parabolaThe ball has a velocity to the The ball has a velocity to the right equal to the velocity of right equal to the velocity of the planethe plane111101/14/1901/14/19Galilean Relativity – Example, conclusionGalilean Relativity – Example, conclusionThe two observers disagree on the shape of the ball’s pathThe two observers disagree on the shape of the ball’s pathBoth agree that the motion obeys the law of gravity and Newton’s Both agree that the motion obeys the law of gravity and Newton’s laws of motionlaws of motionBoth agree on how long the ball was in the airBoth agree on how long the ball was in the airConclusion:Conclusion: There is no preferred frame of reference for describing There is no preferred frame of reference for describing the laws of mechanicsthe laws of mechanics121201/14/1901/14/19Galilean Relativity – LimitationsGalilean Relativity – LimitationsGalilean Relativity does Galilean Relativity does notnot apply to experiments in electricity, magnetism, apply to experiments in electricity, magnetism, optics, and other areasoptics, and other areasResults do not agree with experimentsResults do not agree with experimentsThe observer should