Midterm Study Guide Part 2

True or False

The rate of attenuation is attenuation coefficient

• True

• False

If an 8 MHz pulse travels to a depth of 4 cm, the total attenuation would be

• -2 dB

• -4 dB

• -8 dB

• -16 dB

Answer explanation

8MHz/2 = -4 dB (attenuation coef.); -4 dB x 4cm= -16 dB

If an 8 MHz pulse travels to a depth of 5 cm, what is the total attenuation?

• -2 dB

• -4 dB

• -10 dB

• -20 dB

Answer explanation

8 MHz/2= -4 dB (attenuation coef.); -4 dB x 5 cm= -20 dB

What are the units of attenuation?

• dB/cm

• dB

• MHz

• cm

What happens to most of sound energy in soft tissue?

• Reflects back in soft tissue

• Absorbed as heat energy

• Reflects heat energy

• Absorbed energy

What happens to 10.0W if there is an increase of 3dB?

• 5.0W

• 20.0W

• 100.0W

• 200.0W

When a wave's intensity doubles, the relative change is

• +3dB

• +10dB

• -3dB

• -10dB

When intensity increases ten-fold, the relative change is

• +3dB

• +10dB

• -3dB

• -10dB

When the intensity if reduced to 1/2 it's original valve, the relative change is

• +3dB

• +10dB

• -3dB

• -10dB

When the intensity is reduced to 1/10 its original value, the relative change is

• +3dB

• +10dB

• -3dB

• -10dB