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A sound level of 50 decibels is a) 2.5 times as intense as a sound of 20 decibels. b) 6.25 times as intense as a sound of 20 decibels. c) 10 times as intense as a sound of 20 decibels. d) 100 times as intense as a sound of 20 decibels. e) 1000 times as intense as a sound of 20 decibels.

Short Answer

Expert verified
Answer: The intensity of a 50-decibel sound is 1000 times as intense as a sound of 20 decibels.

Step by step solution

01

Write the given values and formula

We know that: - A 50-decibel sound has a decibel level of 50 dB - A 20-decibel sound has a decibel level of 20 dB The formula to convert decibel levels to intensities is: \( dB = 10 \times log_{10}(\frac{I}{I_0}) \)
02

Find the ratio of intensities#

First, let's consider the 50-decibel sound. Let \(I_1\) be its intensity. Using the formula, we have: \( 50 = 10 \times log_{10}(\frac{I_1}{I_0}) \) Now consider the 20-decibel sound. Let \(I_2\) be its intensity. Using the formula, we have: \( 20 = 10 \times log_{10}(\frac{I_2}{I_0}) \) We need to find the ratio \(\frac{I_1}{I_2}\).
03

Solve the equations for \(I_1\) and \(I_2\)

First, divide both sides of the equations by 10: \( 5 = log_{10}(\frac{I_1}{I_0}) \) \( 2 = log_{10}(\frac{I_2}{I_0}) \) Now, eliminate the logarithms using the property \(a = log_{10}(b) \Rightarrow b = 10^a\): \( I_1 = I_0 \times 10^5 \) \( I_2 = I_0 \times 10^2 \)
04

Calculate the intensity ratio

The intensity ratio between the two sounds can be found by dividing \(I_1\) by \(I_2\): \( \frac{I_1}{I_2} = \frac{I_0 \times 10^5}{I_0 \times 10^2} \) Simplify the expression by canceling the \(I_0\) terms: \( \frac{I_1}{I_2} = \frac{10^5}{10^2} \) Now, use the property \( \frac{a^b}{a^c} = a^{b-c}\) for exponents: \( \frac{I_1}{I_2} = 10^{(5-2)} \) \( \frac{I_1}{I_2} = 10^3 \) Thus, the intensity of a 50-decibel sound is 1000 times as intense as a sound of 20 decibels.
05

Select the correct answer

The intensity ratio \(\frac{I_1}{I_2}\) is 1000, which corresponds to option (e). Hence, the correct answer is: e) 1000 times as intense as a sound of 20 decibels.

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