Physics Module 1 Word Scramble
|
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
| Term | Definition |
| sound | the transmission of mechanical vibrations through a medium |
| wave | a mechanism which transfers energy, not matter |
| compression | region of highest acoustic variables (pressure, density, temp, & particle motion) |
| rarefaction | region of lowest acoustic variables (pressure, density, temp, & particle motion) |
| mechanical waves | need a medium to propagate (sound is an example) |
| electromagnetic waves | able to propagate in either a medium or a vacuum (light, heat, gamma rays, TV signals are all examples) |
| transverse waves | particle motion that is PERPENDICULAR to the wave propagation direction |
| longitudinal waves | particle motion that is PARALLEL to the wave propagation direction; moves along/in the same direction |
| acoustic variables | mechanical changes in the medium that are measured in 4 physical quantities |
| pressure (P) | force/unit area |
| acoustic pressure | the force of compression applied to a unit area of the medium by the sound wave |
| density (p) | mass per unit volume |
| temperature | the degree or intensity of heat present in a substance or object |
| particle motion | particles vibrate back & forth in their original position & do not travel with the wave |
| frequency (f) | a measure of how many times an event occurs in time |
| infrasound | below human's ability to hear (0 Hz - 20 Hz) |
| audible sound | 20 Hz - 20 KHz |
| ultrasound | above human's ability to hear (>20 KHz) |
| diagnostic ultrasound | 2 MHz - 12 MHz |
| period (T) | time needed to complete one cycle |
| wavelength | the physical distance one cycle occupies |
| propagation velocity (c) | the distance sound can travel per unit of time |
| amplitude (A) | the maximum variation of an acoustic variable from its mean value; a measure of how big or how strong |
| power (W) | the rate at which energy is transferred |
| intensity (I) | the concentration of power per unit area |
| elasticity | the ability of an object to return to its original shape after being mechanically deformed by an external force |
| compressibility | a measure of how much the volume of an object changes when pressure is applied to it |
| density | mass/unit volume |
| stiffness | the inverse of compressibility |
| bulk modulus | similar to stiffness |
| decibels (dB) | units used to measure the intensity of a sound by comparing it with a given level on a logarithmic scale |
| reflection | a change in direction of the propagating acoustic energy as it strikes the boundary between two mediums & returns to the source |
| specular reflection | occurs when an ultrasound wave is incident on to a large, smooth surface |
| diffuse reflection | occurs when the ultrasound wave is incident on to a rough, irregular surface |
| Rayleigh scattering | occurs when the reflecting structures are much smaller than the wavelength of the incident ultrasound wave |
| acoustic impedance | the resistance to ultrasound travelling through a medium |
| angle of incidence | formed between the direction of the ultrasound wave (beam direction) & the line perpendicular to the interface |
| normal incidence | occurs when the ultrasound beam is orthogonal (perpendicular) to the interface |
| oblique incidence | occurs when the ultrasound beam is not orthogonal to the interface |
| refraction | occurs when an incident ultrasound beam changes direction or bends on the transmission side of the interface |
| angle of transmission | the angle made by the direction of the transmitted ultrasound wave (beam direction) and the perpendicular to the interface (normal line) |
| Snell's law | the ratio of propagation speeds for two mediums in contrast is proportional to the ratio of the Sines of two angles: the angle of incidence & the angle of transission |
| degree of refraction | the absolute difference between the incident and transmitted angles |
| critical angle | incident angle at which total internal reflection occurs |
| attenuation | the reduction in intensity & amplitude of an ultrasound wave as it travels through a medium |
| attenuation coefficient | the amount of attenuation per cm (unit dB/cm) per MHz of frequency |
| half intensity depth | depth at which the intensity is reduced to 1/2 of its original value |
| simple harmonic motion | the vibration of a source to create motion |
| meter | the distance light travels in a vacuum |
| acoustic intensity | acoustic power per unit area of the sound beam |
| transmission | portion of the energy transmitted through an interface |
Created by:
ginaliane
Popular Physics sets