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Waves and Wave Interactions. Mr. Dunk Pre-AP Physics Pearland High School. What are waves?. one way to transport energy from place to place is by transporting an object another (more complicated) way is by the use of waves
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Waves and Wave Interactions Mr. Dunk Pre-AP Physics Pearland High School
What are waves? • one way to transport energy from place to place is by transporting an object • another (more complicated) way is by the use of waves • a wave involves some quantity or disturbance that changes in magnitude with respect to time at a given location and changes in magnitude from place to place at a given time
Types of Waves • some waves occur only in material media (mechanical waves), others are not restricted to material media • wave – a disturbance that propagates through a medium or space (transfer of energy without large-scale transfer of matter)
Examples of Waves • examples of waves that move through material media • waves in water • shock wave of an explosion • sonic boom • ?
Examples of Waves • examples of waves that do not require material media • light • radio waves • X-rays • ?
Mechanical Waves • mechanical wave – a disturbance in the equilibrium positions of matter, the magnitude of which is dependent on location and on time; must have a source of energy; must have an elastic medium
Transverse Waves • transverse waves – traditionally, crest and trough waves; the displacement of the particles of the medium caused by the pulse is perpendicular to the direction in which the pulse travels; can be a crest, a trough, or both
Pulses and Continuous Waves • pulse – a single, non-repeated disturbance • continuous wave (wave train) – caused by a periodic succession of pulses
Longitudinal Waves • longitudinal (compression or rarefaction) waves – displacement of particles of the medium is parallel to the direction in which the pulse travels
Radiation • radiation – propagation of energy by means of electromagnetic waves; does not need a medium for propagation
Wavelength • wavelength () – distance between any particle in a wave and the nearest particle that is in phase with it; distance advanced by the wave motion in one period
Velocity of a Wave • the speed of a wave depends on the nature of the wave disturbance and on the medium through which it passes (sometimes depends on , e.g. a dispersive medium)
Energy and Waves • equilibrium positions; related to the energy flow in the system • energy transported (or expended) per unit of time is the power transmitted by the wave • the rate of transfer of energy (or the power transmitted by a wave system) is proportional to the square of the wave amplitude and also to the square of the wave frequency
Amplitude • amplitude – the maximum displacement of the vibrating particles of the medium from their equilibrium point
Damping • damping – the reduction in amplitude of a wave due to the dissipation of wave energy as it travels away from the source
Constructive Interference • constructive interference – when individual displacements on the same side of the equilibrium position are added together to form the resultant wave (resultant is larger than either of the component waves)
Destructive Interference • destructive interference – when individual displacements on opposite sides of the equilibrium position are added together to form the resultant wave (resultant is smaller than either of the component waves)
Superposition • superposition – the combination of two overlapping waves
Reflected Waves • at a free boundary, waves are reflected • at a fixed boundary, waves are reflected and inverted
Standing Waves • standing wave – a wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere
Nodes and Antinodes • node – a point in a standing wave that always undergoes complete destructive interference and therefore is stationary • antinode – a point in a standing wave, halfway between two nodes, at which the largest amplitude occurs
