# Physics Lect 6

 Wave formulas relating frequency and wavelength v = f λvelocity = (frequency)(wavelength)use only to find frequency or wavelength, velocity is independent of these two Frequency the # of waves that pass a fixed point per second Period the # of seconds it takes for a complete wavelength to pass a fixed pointT = 1 / f What factors affect the speed of a wave Only medium affects the velocity of a wave(1) its elasticity (resistance to change in shape) - stores U - greater eleasticity speeds waves up(2) its inertia (resistance to change in motion) - stores K.E. - greater inertia slows waves down Generally, stiff mediums ___ ___ waves. speed, up Generally, heavy mediums ___ ___ waves. slow, down What effect does temperature have waves traveling through a gas? It increases velocity as it increases (more K.E.) Velocity relates to what for surface waves? with surface waves, velocity increases with depth What is the elastic component of surface waves? gravity How is power measured? Power is measured in terms of intensity (I)I is proportional to A2 and f2 for all wavesIt is related to itself - dB (decibles)~ however many zeros you add to an intensity - take that integer and add a zero behind it, this will give you the decible jump Beats occurs when two waves with slightly different frequencies interfere with eachotherat some points there are "in phase" (constructive) and sometimes they are out of phase (destructive)fbeat = | f1 - f2 | Pitch For sound waves, pitch correlates with frequencyA high note will have a high pitch and a high frequency What happens to waves at an interface of media? (1) some (or all) of the energy is REFLECTED if it is reflected off of a more dense medium than the medium it is coming from --> the wave is inverted (180° phase shift) if it is reflected off a less dense medium --> the wave reflects back upright (no phase shift)(2) the remaining energy is REFRACTED into the new mediumthese waves will have the SAME frequency, a DIFFERENT wavelength, and a SMALLER amplitude Standing Waves waves that contain nodes and antinodes node is "still" when observedantinodes have the greatest displacement from zero Harmonic series a list of wavelengths that create standing waves for a specific length of "string"listed from largest to smallest∴ 1st has the longest λ and the fewest nodes (2)if both ends are secure:L = nλn / 2 (n = 1, 2, 3...) if one end is loose:L = nλn / 4 (n = 1, 3, 5...) Simple Harmonic Motion motion that demonstrates a sine function of timeobjects in simple harmonic motion share certain properties: 1) acceleration is ∝ displacement but opposite in sign; 2) a & d are related by f2; 3) oscillates between kinetic and potential E The Doppler Effect when a source moves relative to the observer it can change the frequency and the wavelength of the wave that reaches the observer Doppler Effect Formulas Δf / fs = v / cΔλ / λs = v / cfs: frequency produced by the sourceλs: wavelength produced by the sourcev: the net speed of the source and the object (if they are moving in the same direction you subtract their velocities; if they are moving in opposite directions you add their velocities) With the Doppler Effect, what happens as the source and the observer grow closer? The frequency increases and the wavelength decreases What experiences no Doppler Effect? Objects moving in the same direction at the same speedv = 0 (because if they are moving in the same direction we subtract their speeds) Authorlaskiru ID59815 Card SetPhysics Lect 6 DescriptionWaves Updated2011-01-14T19:16:06Z Show Answers