University:
Arizona State University
Course:
PHYS 102 | Introductory Physics I
Academic year:

2024
Views:

433

Pages:

4
Author:

Mohammed N.

Periodic wave A wave is called periodic if it repeats itself after a constant interval of time T. Periodic waves: The period T represents the time necessary for a complete cycle of oscillation to be completed. the frequency f is the number of oscillations occurring in the period of time T. The distance between the highest points of the consecutive wave (ridges), is called 'wavelength' and is indicated by the symbol of lambda λ. The amplitude is the maximum displacement of the equilibrium position. The angular frequency, also called pulsation, is the quantity Sound wave A sound wave, or acoustic wave, is a simple vibratory movement that spreads mechanically. It's a longitudinal wave. Sound is a physical phenomenon that needs a source, a vibrating object, and an elastic means of propagation in which waves can travel to exist. Air, water, wood, metals, concrete, bricks and glass can vibrate and propagate sound waves. Sound energy is a mechanical (or kinematic) energy that, starting from the source, radiates in the form of waves through the means of propagation to the listener, without transporting matter. Sound waves are divided into: sounds (20-20,000 Hz); ultrasound (> 20,000 Hz); infrasound (< 20 Hz). The human ear perceives only sounds. The wave depends on height (as the frequency increases, the height of the wave increases and vice versa), magnitude (this is the energy carried by the wave and makes it possible to distinguish between loud and weak sounds), timbre (it makes it possible to distinguish between several sounds emitted by different sources). Doppler effect The Doppler effect is a physical phenomenon that consists in the apparent change, with respect to the original value, of the frequency or wavelength perceived by an observer reached by a wave emitted by a source that is in motion with respect to the observer himself. Still source and moving observer: f is the emission frequency. Suppose that the observer is moving with speed vr, moving away from the source, the frequency f' is: Vice versa, suppose that the observer is moving with speed vr, approaching from the source, the frequency f' is: Source in motion and stationary observer: Suppose the source is moving away from the observer at vr speed, the frequency f' is: Vice versa, suppose that the source is approaching the observer with speed vr, the frequency f' is: