Question

A sound wave with a power of 8.8 × 10–4 W leaves a speaker and passes through section A, which has an area of 5.0 m2.

What is the intensity of sound in this area? (Intensity = I = )

1.8 × 10–4 W/m2
1.8 × 10–6 W/m2
1.6 × 10–4 W/m2
1.6 × 10–6 W/m2

Answer 1

To calculate the intensity of the sound (I), we can use the formula:

\[
I = \frac{P}{A}
\]

where:
- \(P\) is the power of the sound wave,
- \(A\) is the area through which the sound passes.

Given:
- \(P = 8.8 \times 10^{-4} \, \text{W}\)
- \(A = 5.0 \, \text{m}^2\)

Now, substituting the values into the formula:

\[
I = \frac{8.8 \times 10^{-4} \, \text{W}}{5.0 \, \text{m}^2}
\]

Calculating this gives:

\[
I = 1.76 \times 10^{-4} \, \text{W/m}^2
\]

This can be rounded to:

\[
I \approx 1.8 \times 10^{-4} \, \text{W/m}^2
\]

Thus, the intensity of sound in this area is:

\[
\text{Intensity} = 1.8 \times 10^{-4} \, \text{W/m}^2
\]

So the correct answer is:

**1.8 × 10–4 W/m²**.