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The intensity I of light from an isotrop...

The intensity I of light from an isotropic point source is determined as a function of distance r from the source . Figure 32-29 gives intensity I versus the inverse square `r(-2)` of that distance . The vertical axis scale is set by `I_(s)=200 W//m^(2)` and the horizontal axis scale is set by` r_(s)^(-2)=8.0m^(2)` . What is the power of the source ?

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`4pi (30) ~~ 2.5xx10^(2) W`
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