Physics Exam 1 Review

Intensity is proportional to ______ squared.

amplitude

What process causes high-frequency ultrasound waves to have less depth penetration than low-frequency ultrasound waves?

Increased attenuation of higher frequencies

What two parameters must be known for proper echo display?

Direction of the echo and distance to the reflector

What factor determines how much of an incident sound wave is reflected back and how much is transmitted?

Impedance

True/False: Liver parenchyma is an example of a specular reflector.

False

What is the attenuation rate for soft tissue?

0.5 dB/cm/MHz

Which term best describes the reduction in a sound wave’s amplitude as it propagates through tissue?

Attenuation

For soft tissues, the attenuation coefficient at 5MHz is approximately:

2.5 dB/cm

Amplitude and intensity are indicators of sound____.

strenght.

An increase in frequency will cause an increase in which of the following parameters?

Attenuation

With perpendicular incidence, the reflected intensity depends on the_____

impedance difference

What does Snell’s Law predict?

Amount of sound beam refraction

Which of the following tissues has the highest attenuation rate?

Bone

What term is used to describe the maximum variation in an acoustic variable?

Amplitude

What does an Intensity Reflection Coefficient of 0.25 tell us?

75% of the intensity is transmitted through an interface and 25% is reflected back to the transducer

What 2 factors must be present before refraction of a sound wave can occur at an interface?

Non-perpendicular beam incidence and different speeds of sound at the interface

For specular reflectors, the angle of reflection is equal to the____.

Angle of incidence

Which term describes bending of the sound beam as it passes through an interface at non-perpendicular incidence?

Refraction

True/False: No reflection will occur with perpendicular incidence if the media impedances are equal.

True