Physics Section 11.3 Apply the properties of waves A wave is a periodic disturbance that transfers energy by the vibration of matter, rather than the transfer.

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1 Physics Section 11.3 Apply the properties of waves A wave is a periodic disturbance that transfers energy by the vibration of matter, rather than the transfer of matter. An electromagnetic wave does not require a physical medium through which to travel. A mechanical wave is a wave that requires a physical medium in which to travel (propagate).

2 The highest point above the equilibrium position is a crest. The lowest point below the equilibrium is a trough. The distance between any two adjacent crests(or troughs) is the wavelength. (λ) Types of Mechanical Waves 1.Transverse wave- the particles of the medium vibrate perpendicular to the direction the wave is traveling.

3 2. Longitudinal wave – the particles of the medium vibrate parallel to the direction the wave moves. A compression is a region where the medium particles are closer to each other than the equilibrium. A rarefaction is a region where the medium particles are further apart than the equilibrium. A longitudinal wave is sometimes called a density or pressure wave.

4 The period of a wave is the time it takes for a complete wavelength to pass a given point. The frequency of a wave is the number of wavelengths to pass a point each second. Wave Speed Formula V = f λ v = velocity (m/s) f = frequency (hz) λ = wavelength (m) For a constant velocity, the frequency and the wavelength of a wave vary inversely.

5 problems Sound travels at a velocity of 240 m/s in a given medium. Find the wavelength of a sound whose frequency is 120 hz. A wave has a period of 4.2 x 10 -5 s and a wavelength of 1.8 x 10 -3 m. Find its velocity.

6 For a mechanical wave, the power is directly proportional to the square of the amplitude and the frequency. Damping is the reduction in the amplitude of a wave as its energy dissipates.

7 assignment Page 388 Problems 1 - 5