Wave Mechanics Physics 1
What is a wave? A wave is: an energy-transferring disturbance moves through a material medium or a vacuum
Categories of Waves Mechanical – require a material medium Electromagnetic – can move through empty space (vacuum)
Types of Waves In a transverse wave, the displacement of the particles of the medium is perpendicular to the direction of wave motion.
Types of Waves
In a longitudinal wave, the displacement of the particles of the medium is parallel to the direction of wave motion.
Types of Waves
Wave Characteristics frequency ( f ) period ( T ) amplitude (A) phase wavelength ( ) speed ( v )
Wave Characteristics The frequency of a wave is the number of complete vibrations (cycles) per unit of time. 1 cycle per second = 1 hertz (Hz)
Wave Characteristics The period of a wave is the time for the completion of a cycle.
Wave Characteristics The amplitude of a wave is the maximum displacement of the particles in a medium from equilibrium. The amplitude is related to the energy in the wave.
Wave Characteristics The phase of a wave describes the position and direction of any particle in an wave- carrying medium.
Wave Characteristics
The wavelength of a wave measures the distance between any two consecutive points in-phase.
Wave Characteristics The speed of a wave depends on the properties of the medium through which it is traveling. v = d/t = /T = f
Wave speed in a string. v = speed of the transverse wave (m/s) F = tension on the string (N) or m/L = mass per unit length (kg/m) v = speed of the transverse wave (m/s) F = tension on the string (N) or m/L = mass per unit length (kg/m) The wave speed v in a vibrating string is determined by the tension F and the linear density , or mass per unit length. L = m/L
Wave Properties rectilinear propagation reflection refraction interference diffraction
Wave Properties The direction of propagation of the advancing wave is perpendicular to the wave front. This is due the wave property of rectilinear propagation.
Wave Properties When wave encounters a boundary between two media of different propagation speed, some wave energy can be turned back. This is called the wave reflection.
Wave Properties fixed end free end
Wave Properties incident wave reflected wave
Wave Properties When a wave passes through the boundary of two media of different propagation speed, the path of wave energy will bend. This is called the wave refraction.
Wave Properties When two wave pulses encounter each other in a medium, the wave pulses will superpose beyond the barrier. This is called the wave interference.
Wave Properties Principle of Superposition - When two waves traveling independently through the same medium, the resultant displacement of any particle at a given time is the vector sum of the displacements that the individual waves acting alone would give it.
Wave Properties Constructive Interference
Wave Properties Destructive Interference
Wave Properties When a wave passes through an opening in a barrier, the wave energy will spread out beyond the barrier. This is called the wave diffraction.
Standing Waves A standing wave is the result of two waves of the same frequency and amplitude traveling in the opposite directions through the same medium.
Standing Waves A point of no disturbance in a standing wave is called a node. A point in standing wave where the amplitude is maximum is called an antinode. (sometimes called loops and are located between the nodes)
Standing Waves The fundamental frequency (or natural frequency) of a medium occurs when it vibrates with the simplest standing wave – two nodes and one antinode.
Standing Waves The harmonic of a wave is a component frequency of the wave that is an integer multiple of the fundamental frequency.
Harmonic Series