# Waves and Sound

## 41 terms · Physics Note Cards

### Simple Harmonic Motion

Any periodic motion that is the result of a restoring force that is proportional to displacement

### Amplitude

Max displacement from equalibrium position (Distance from equalibrium to the crest or trough)

### Period

Time it takes to complete one cycle

### Frequency

Number of oscillations in a unit of time. Reciporcal of time period: f= 1/T

### Medium

Anything through which a wave travels (air, water, spring, earth)

### Transverse wave

A wave whose particles vibrate perpendicularly to the direction of wave motion. (Light waves, electromagnetic waves)

Top of a wave

Bottom of a wave

### Wavelength

The length of 1 cycle of a wave

### Longitudinal wave

A wave whose particles vibrate parallel to the direction of wave motion. (Compressional waves, requires a medium, sound waves)

### Constructive Interference

To waves interfere with eachother and build up (Interference in which individual displacements on the same side of the equalibrium position are added together to form the resultant wave)

### Destructive Interference

To waves interfere with eachother and switch places (Interference in which individual displacements on opposite sides of the equalibrium position are added together to form the resultant wave)

### Standing wave

A wave pattern that results when two waves of the same frequency, wavelength, and amplitude travel in opposite directions and interfere (standing wave)

### Node

A point in a standing wave that always undergoes complete destructive interference and therefore is stationary (points that the wave hits equalibrium)

### Antinode

A point in a standing wave halfway between two nodes, at which the largest amplitude occurs (top of crests and troughs)

### Compression

The region of a longitudinal wave in which density and pressure are greater than normal

### Rarefraction

The region of a longitudinal wave in which density and pressure are less than normal

### Decibel level

Relative intensity, determined by relating intensity of sound waves to intensity at the threshold of hearing

### Resonance

A conditin that exists when frequency of a force applied to a system matches the natural frequency of a vibration of the system

### Fundamental frequency

The lowest frequency of a vibration of a standing wave (determines pitch)

### Harmonic series

A series of frequencies that includes fundamental frequency and integral multiples of the fundamental frequency

### Beats

Interference of waves of slightly different frequencies traveling in the same direction, perceived as a variation in loudness

### Electromagnetic wave

Transverse wave consisting of oscillating electric and magnetic fields at right angles to eachother

### Wave front

Centers of compressions

### Shock wave

Carries a great deal of energy concentrated on the surface of one

### Harmonics

The frequencies of sounds

### Superposition priciple

That waves can occupy the same space at the same time

Pressure waves

### Pitch

Highest or lowest sounds a object can make

### What affects the speed of sound?

the medium, wavelength, and frequency

### Doppler effect

A frequency shift that is the result of relative motion between the source of waves and an observer

### What unit measures the intensity of sound, and what kind of scale is this unit based on?

Decibles (dB), logarithmic scale

### What determines whether you can hear a sound or not?

Intensity and frequency

Audible

### Timbre

The quality of a steady musical sound that is the result of a mixture of harmonics present at different intensities (sound quality)

### Beats

A variation in loudness

F=nv/2L

F=nv/4L

f=nv/2L

### If both ends of a pipe are open..

All harmonics are present

### If one end of a pipe is open...

Only odd harmonics are present