Logarithms & Decibels Flashcards
The logarithm of a numeral is defined as how many times ___ must be multiplied together to get that numeral.
a. 1
b. 2
c. 5
d. 10
d. 10
What is a decibel?
a. the absolute value of a number
b. a range of values
c. a relationship between two numbers
d. none of the above
c. a relationship between two numbers
Decibel notation is a ____ between two numbers.
a. difference
b. sum
c. product
d. ratio
d. ratio
Which of the following reports the relative strength of an ultrasound wave?
a. decibels
b. watts
c. W/cm^2
d. pascals
a. decibels
The scale associated with decibel notation is ____.
a. linear
b. discrete
c. logarithmic
d. additive
c. logarithmic
What is the decibel representation when an acoustic signal is amplified?
a. positive
b. negative
c. equal to zero
a. positive
What is the decibel notation for an acoustic signal that is attenuated?
a. positive
b. negative
c. equal to zero
b. negative
The intensity of a signal declines from 1.5 mW/cm^2 to 0.75 mW/cm^2. How many decibels is this change in intensity?
a. 3 dB
b. 0.75 dB
c. -0.75 dB
d. -3 dB
d. -3 dB
The power in a wave is increased to ten times its original value. How many decibels describe this change?
a. 3
b. 6
c. 10
d. 20
c. 10
How many decibels represent a 100-fold increase in the intensity of an acoustic pulse?
a. 10
b. 20
c. 100
d. 6
b. 20
The intensity of an ultrasound wave is change by -6 dB. This means that the current intensity is ____ as much as its original level.
a. one-tenth
b. four times
c. one-fourth
d. one-sixth
c. one-fourth
What units are used to describe attenuation?
a. watts
b. watts/cm^2
c. macro
d. decibels
d. decibels
What does a 3 dB change in a value intensity mean?
a. the value has doubled
b. the value has tripled
c. the value has increased 30%
d. the value has increased ten times
a. the value has doubled
