The intensity of a certain spherical wave is 8.0 W/m² at a distance of 1.0 m from the source.If the medium is isotropic and nonabsorbing,the intensity 100 m from the source is A)8.0 W/m² B)6.4 $\times$ 10^-4 W/m² C)1.9 $\times$ 10^-4 W/m² D)8.0 $\times$ 10^-4 W/m² E)1.9 $\times$ 10^-6 W/m²

Question

Quizplus · Accepted Answer

The intensity of a spherical wave varies inversely with the square of the distance from the source. Therefore, at a distance of 100 m from the source, the intensity will be:

I = 8.0 W/m^2 * (1 m / 100 m)^2 = 8.0 * 10^-4 W/m^2

We can convert this to scientific notation as 8.0 * 10^-4 W/m^2 = 8.0 * 10^10 * 10^-14 W/m^2 = 8.0 * 10^10 nW/m^2.

Using the same unit conversion as in the question, we get:

8.0 * 10^10 nW/m^2 = 8.0 * 10^10 * 10^-9 W/m^2 = 8.0 * 10^1 W/m^2

Therefore, the answer is choice D, 8.0 × 10^1 W/m^2.

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The Intensity of a Certain Spherical Wave Is 8 $\times$ 10^-4 W/m²
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