Ultrasound Physics SPI exam questions with correct answers

length is measured in - Answer- cm, feet area is measured in - Answer- cm^2, feet^2 volume is measured in - Answer- cm^3, feet^3 percent is not - Answer- a unit increase by a factor means - Answer- to multiply decrease by a factor means - Answer- to divide how many hertz is 3 MHZ - Answer- 3,000,000 how much bigger is a billion than a million - Answer- 1000 times how many milliliters are contained in a jar filled with 5 liters of fluid - Answer- 5000 how many liters are in 80 ml of fluid - Answer- 0.080 macro means - Answer- bigger micro means - Answer- smaller the effects of the medium upon the sound wave - Answer- acoustic propagation properties the effects of the sound wave upon the biologic tissue - Answer- biologic effects a type of wave that carries energy not matter from place to place - Answer- sound areas of increased pressure and density - Answer- compressions areas of decreased pressure and density - Answer- rarefractions sound must travel through a medium, sound cannot travel through a - Answer- vacuum sound is a - Answer- mechanical, longitudinal wave sound travels in a - Answer- straight line acoustic variables identify which waves are sound waves, when an acoustic variable changes in time a - Answer- sound wave is present three acoustic variables are - Answer- pressure, density, and distance pressure is - Answer- a concentration of force within an area pressure is found by - Answer- force/area unit of pressure is - Answer- pascals (Pa) density is - Answer- concentration of mass within a volume unit of density is - Answer- kg/cm^3 distance is - Answer- measure of particle motion unit of distance - Answer- mm or cm unit of density - Answer- kg/cm^3 a transverse wave has particles that move in a - Answer- perpendicular direction (right angles or 90 degrees) to the wave direction a longitudinal wave has particles move back and forth in the - Answer- same direction as the wave acoustic variables - Answer- identify which waves are sound waves acoustic parameters - Answer- describe the features of a particular sound wave period is measured in - Answer- units of time (microsec) the time required to complete a single cycle example would be -high school class is 50 minutes - Answer- period period is determined by the - Answer- sound source Can period be changed by the sonographer? - Answer- No, cannot be changed by sonographer frequency is - Answer- the number of certain events that occur in a particular time duration in diagnostic ultrasound the frequency of a wave is the number of cycles of an acoustic variable that occur in - Answer- one second units of frequency - Answer- per second, 1/second, hertz, Hz hertz is another way of saying - Answer- per second Frequency is determined by the - Answer- sound source Can frequency be changed by the sonographer? - Answer- No, cannot be changed by sonographer typical frequency values include - Answer- 2 MHz to 15 MHz humans can hear frequency's - Answer- between 20 Hz and 20,000 Hz ultrasound can hear frequency's - Answer- greater than 20,000 Hz (too high for humans to hear) infrasound is - Answer- less than 20 Hz (below human and ultrasound) period and frequency are - Answer- reciprocals and an inverse relationship when period increases - Answer- frequency decreases When period decreases - Answer- frequency increases when period is unchanged - Answer- frequency is also unchanged when dealing with frequency and period remember to use units of - Answer- sec & Hz three bigness parameters - Answer- amplitude, power, intensity amplitude, power, and intensity describes a sound beams - Answer- strength amplitude, power, and intensity can all be changed by the sonographer and - Answer- decreases as sound travels amplitude, power, and intensity are initially determined by - Answer- the sound source amplitude is - Answer- the difference between the average value and the maximum value of an acoustic variable. The variation of an acoustic variable. units of amplitude include - Answer- pascals, grams/cubic cm, cm, inches, units of distance Bigness may be expressed in - Answer- decibels (dB) the difference between maximum and minimum values of an acoustic variable is called - Answer- peak to peak amplitude amplitude is half of the - Answer- peak to peak amplitude power is - Answer- the rate at which work is done, or the rate of energy transfer unit of power - Answer- watts Can power be changed by the sonographer? - Answer- Yes, power can be changed by the sonographer. Power is determined by - Answer- Sound source (initially) Power decreases as sound travels. power is proportional to the waves - Answer- amplitude squared when the amplitude is tripled the power is increased by a factor of - Answer- 9