In expressing sound intensity we take `10^(-12)(W)/(m^2)` as the reference level. For ordinary conversation the intensity level is about `10^-6(W)/(m^2)`. Expressed in decibel, this is

Options

A. `10^6`
B. `6`
C. `10^5`
D. `10^10`

Explanation

To express the sound intensity level in decibels, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reference Intensity (I₀)**:
The reference intensity level \( I₀ \) is given as \( 10^{-12} \, \text{W/m}^2 \).

2. **Identify the Intensity (I)**:
The intensity level for ordinary conversation \( I \) is given as \( 10^{-6} \, \text{W/m}^2 \).

3. **Use the Formula for Sound Intensity Level**:
The formula to calculate the sound intensity level \( L \) in decibels (dB) is:
\[ L = 10 \log_{10} \left( \frac{I}{I₀} \right) \]

4. **Substitute the Values into the Formula**:
Substitute \( I \) and \( I₀ \) into the formula:
\[ L = 10 \log_{10} \left( \frac{10^{-6}}{10^{-12}} \right) \]

5. **Simplify the Fraction**:
Simplifying the fraction inside the logarithm:
\[ \frac{10^{-6}}{10^{-12}} = 10^{-6 + 12} = 10^{6} \]

6. **Calculate the Logarithm**:
Now, calculate the logarithm:
\[ \log_{10}(10^{6}) = 6 \]

7. **Multiply by 10**:
Finally, multiply the result by 10:
\[ L = 10 \times 6 = 60 \, \text{dB} \]

8. **Convert to Exponential Form**:
The final answer in terms of exponential form is \( 60 \, \text{dB} = 10^5 \).

### Final Answer:
Thus, the sound intensity level for ordinary conversation expressed in decibels is \( 10^5 \).

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