PHY 102 1st Edition Outline of Last Lecture I Simple Harmonic Oscillation a SHO definition b Period c Examples i Hooke s Law ii Pendulum II Waveform Terms a Properties of waves b Definitions III Sound as an Analogy a Tuning fork b Sound waves c Types of waves IV Wave Forms Outline of Current Lecture i Continued Examples a Example 1 b Example 2 c Example 3 These 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 d Example 4 ii Other Properties of Waves a Polarization b Diffraction c Interference d Doppler Shift Effect iii Light Properties iv Electricity a Example Discharges b Electrical Charges c Electrical Field Strength d Coulomb s Law Current Lecture I Continued Examples a The period of oscillation is 2 7 seconds F 1 t F 1 2 7 seconds F 1 2 7 Hertz or Hz i 1 Hertz 1 cycle second ii Period is the reciprocal of frequency b 3 wave crests pass a point every 10 seconds what is the frequency of the crests F oscillations second 3 oscillations 10 seconds 3 Hz c What is the appropriate frequency of a 6 563 nm wavelength of light 1 nanometer 1x10 9 m and c 3x108 m s x F speed of light 3 0x108m s i Wavelength x frequency speed of the propagation of the wave ii One speed in the universe is constant light 3 0x108m s d A tidal wave is 3m high How energetic is a 6m high tidal wave in comparison to the 3m wave if both are traveling at the same speed E kA2 So a wave twice as high will have 4 times as much energy because of the A2 e How fast is a wave moving if f 3Hz and 2 3 m F 3Hz 2 3 m 2 3 3 6 9 m s f v II Other Properties of Waves a Polarization i Polarized sunglasses cost more because they are like picket fences the light can only come through one way ii When light passes through one lens which allows vertical waves the next lens will be one that only allows horizontal waves blocking almost all waves of light iii Oscillation can be up and down side to side spiral iv Electric field vectors can align and become polarized v When radiation comes through it reduces the glare dramatically vi Used in astronomy to measure magnetic fields in space b Diffraction dispersal of light i When the slight that a ray of light passes through approaches the size of the ray of light the light diffracts and disperses ii Example of a harbor 1 When a wave in a harbor passes through a small opening into the shore the wave starts small and begins to ripple and disperse through the water as it approaches the shore 2 Intensity v distance graph looks like lots of small curves because as the distance grows larger the intensity of the wave grows and diminishes c Interference 2 waves coming together 2 diffraction patterns intersecting i Intensity v distance graph looks very random because the two waves can intersect at the crest points or at the bottom and a crest ii The intensity of a sound varies at different positions of the observer because of interference of waves iii Where the crests of a wave intersect the wave doubles and the sound is observed louder d Doppler Effect sound shifts because of position of the hearer i Also observed in light when galaxies appear red because the universe is expanding and they are moving farther away ii Pitch changes in racecars trains due to the Doppler shift effect III Light a Acts as a particle and a wave depending on the scale i Large scale particle like property light travels in a straight line and creates distinct shadows ii Measured in photons which have properties of a particle while containing a wave of light inside iii Small scale wave like property single slit demo and interference double slit demo IV Electricity a Electrostatic i Example discharges 1 Lightning 2 foot dragging 3 Static cling in dryers ii Electrical charges come in two types and 1 Amber Greek called Electron is associated with 2 Glass associated with 3 Charging by induction and conduction b Action at a distance applying a force without touching the other object i Repelling is from the same charge ii Attracting is from the opposite charge c An object has equal photons and elctrons when electrons are added the object becomes negatively charged d An object can become polarized when the electrons gather in certain areas i Induction not touching ii Conduction touching e More moisture in the air the shorter time the electricity is held in an object V Electrical Charges a Negative electron when electrons are added b Positive proton when electrons are taken away c Charge is measured in Coulombs c i Absolute value of C s ampere 6 215x1018 electrons second d Quantities of charge i Electron 1 6 x 10 19 ii Proton 1 6 x 10 19 VI Electrical Field Strength a E Fe q by definition force per unit charge b Units of E are N c c Parallels W mg where g gravitational field strength d Electric field lines i Directed from positive to negative charge ii Show the path that a positive unit test charge would take 1 Test charge one single proton 2 Field liens appear to exist but have no physical form e Coulomb s Law i Fg GM1M2 r2 Fe kq1q2 r2 or kQq r2 First worked out as a torsion balance