Physics Waves PDF

Physics Waves WAVES A wave is a disturbance or vibration that transmits energy, not matter. Transverse Wave -- Particles move perpendicular to the wave motion Longitudinal Wave -- Particles move parallel to the wave motion Surface Wave -- Combination of 1 and 2 Amplitude -- Max displacement fr...

Physics Waves WAVES A wave is a disturbance or vibration that transmits energy, not matter. Transverse Wave -- Particles move perpendicular to the wave motion Longitudinal Wave -- Particles move parallel to the wave motion Surface Wave -- Combination of 1 and 2 Amplitude -- Max displacement from crest to trough REFRACTION Refraction -- The bending of light as it changes medium Optical Density -- Measure of how difficult it is for light to travel in a substance Angle of Incidence -- Angle between incident ray and normal Angle of Refraction -- Angle between refracted ray and normal A diagram of a refractory ray Description automatically generated When passing from a denser to less dense medium, the light refracts away from the normal. When light travels from less dense to more dense it slows down and bends down the normal When light travels from more dense to less dense it speeds up and bends away from the normal. If the angle is large enough then the angle of reflection will be parallel to the medium boundary Critical Angle -- Oi that results in Or = 90 degrees Oi = Incident Ray Or = Refracted Ray Oc = Normal Total Internal Reflection -- When Oi \> Oc, the light is reflected off the boundary, Oi = Or Snell's Law -- n1SinOi= n2SinOr (N1 = Incident index of refraction, n2 = Refracted index, Oi = Angle of incidence and Or = Angle of Refraction) REFLETION AND TRANSMISSION If the medium the wave travels through stays constant, the waves travel at a uniform speed. Waves act differently as they pass through different mediums. Mediums of different temperature result in different wave speeds. Pulses reflected off of fixed ends will revert and flip upside down. Pulses reflected off of free ends will revert but not flip. Sound waves are transmitted particle to particle through vibrations The closer the particles, the easier it is to vibrate. This is why sound travels faster in solids. INTERFERENCE Superposition Principle -- Sum of the amplitudes of the individuals Constructive Interference -- Waves with the same frequency and phase combine together Destructive Interference -- Waves with the same frequency and opposite phase cancel out STANDING WAVES Standing waves are caused by constructive and destructive interference. Areas of complete destructive interference have no amplitude and are called nodes. Areas of complete constructive interference have max amplitude and are called anti-nodes. When a wave hits a fixed boundary it will reflect and invert its amplitude. If a series of waves are sent along a string, the reflect pulse will interfere. If the waves are sent at just the right frequency we will create a standing wave. SINGLE SLIT DIFFRACTION Diffraction takes place when a wave with a wavelength comparable to or larger than the size of an aperture or an obstacle moves through or past the aperture or obstacle. In general. The larger the wavelength, the larger the effect. Diffraction is caused by objects within the medium that interact with the wave, it is not caused by two mediums and their boundary. The smaller the aperture b the greater the diffraction effect STANDING WAVES 2 Standing Waves are a unique situation where two waves with equal amplitude, frequency, and wavelength, but traveling in opposite directions meet.  Standing waves on strings -- Two fixed ends For fixed ends f = nv/2L Standing waves in pipes -- One fixed end, one open end F = nv/4L WAVES 2 Beats - Periodic and Repeating fluctuations of sound intensity when two sound waves of very similar frequencies interfere with each other A loud sound is heard when constructive interference occurs between two crests or two troughs. No sound is heard when destructive interference occurs between a crest and trough. Amplitude is directly related to loudness, hence the beat pattern that would be consistent with a wave that varies in volume at a regular rate. Beat Frequency -- The rate at which the volume is heard to be oscillating from high to volume. If two complete cycles of high and low volumes are heard every second, the beat frequency is 2hz. The beat frequency between two interfering waves is \| f2 -- f1 \|. SOUND Sound -- Longitudinal waves of pressure that stimulate our ear drums The speed of sound depends on the medium, more dense = faster Pitch is determined by frequency and Volume is determined by Amplitude DOPPLER SHIFT Doppler Effect -- When the sound source moves toward you or when you move toward the sound source, the pitch will seem to increase. If the source approaches a stationary observer, apparent wavelength decreases. Emitted speed is constant, therefore frequency increases. If a source is moving away from the stationary observer, the wavelength increases and frequency decreases. If the source is stationary and the observer is approaching it, apparent wavelength remains the same. For an observer moving away from the source, apparent wavelength increases, therefore apparent velocity decreases.