Ultrasound Physics Ch 1-2 (The Basics & Sound)

Unrelated

not associated

related/proportional

associated or affiliated but not specific

Directly related/proportional

As one increases so does the other

Inversely related/proportional

As one increases the other decreases

Reciprocal

. ex- 2 and 2/10

.when multiplied together the result is one

. special form of inverse

increase by a factor

multiply

.ex- increase by a factor of 6 is 6x larger

Decrease by a factor

Divide by that number

. ex- decrease by a factor of 3 is 1/3

percent is

unitless

10^9

giga(G)- Billion

10^6

mega(M)- Million

10^3

kilo(k)-thousand

10^2

hecto(h)- hundred

10^1

deca(da)- ten

10^-1

deci(d)- tenth

10^-2

centi(c)- Hundredth

10^-3

milli(m)- Thousandth

10^-6

micro(,u)- Millionth

10^-9

nano(n)- Billionth

Billions/billionths

giga & nano (G & n)

millions/millionths

mega & micro (M & ,u)

thousands/thousandths

kilo and milli (k & m)

hundreds/hundredths

hecto and centi (h & c)

tens/tenths

deca & deci (da & d)

sound is a

mechanical wave

molecules in a medium vibrate

back and forth from a fixed point

Can sound travel through a vacuum?

No, it must travel through a medium

Sound travels

in a straight line

Sound waves are longitudinal or transverse waves

longitudinal waves

compressed means

squeezed together

Rarefied means

stretched apart

The 4 acoustic variables rhythmic oscillations are

pressure, density, distance, temperature

Sound waves are also known as

acoustic waves

Pressure units are

Pascals (Pa)

Density units are

kg/cm^3

Distance units are

cm, mm

Temperature units are

Fahrenheit and Celsius

The acoustic parameters that describe the characteristics of sound waves are

1. period

2. frequency

3. amplitude

4. power

5. intensity

6. wavelength

7. propagation speed

In transverse waves particles move

perpendicular to direction the wave propagates

In longitudinal waves particles move

In the same direction that the wave propagates

peaks

max values

troughs

min values

Waves are _________________ when their peaks and troughs occur at the same time and at the same location.

in- phase

Two waves are ________________ when their peaks and troughs occur at different times.

out-of-phase

The following bullet points are describing:

. multiple sound beams travel in a medium arriving at an identical location @ the same time

. waves lose individual characteristics & combine forming a single wave

interference

both in-phase and out-of-phase wave pairs undergo interference; however,

they combine differently

Constructive interference

. in-phase waves

. forms a single wave of greater amplitude, larger wave

Destructive interference

. out-of-phase waves

. forms lesser amplitude, smaller wave

What happens when 2 out of phase waves are of equal amplitude?

. complete destructive interference, they cancel each other out

What happens when the frequencies of waves differ?

both constructive and destructive interference occur

Sound waves are

pressure waves