Sonography Canada Physics Core Practice Exam

The calculation of decibels (dB) when comparing two intensity levels involves a logarithmic relationship where the initial and final intensity levels are divided. The formula used for this is:

\[ \text{dB} = 10 \log_{10} \left( \frac{I_f}{I_i} \right) \]

In this equation, \( I_f \) represents the final intensity, while \( I_i \) represents the initial intensity. By dividing the final intensity by the initial intensity, the logarithmic scale allows us to express the ratio of these two quantities in a more manageable form. This method is particularly advantageous since sound intensities can vary over a wide range of values, and the logarithmic scale compresses this range into a more interpretable format.

The use of division in calculating decibels is essential in acoustics and many applications in sonography, as it helps in understanding the relative change in intensity levels, which directly correlates to perceived loudness.