The intensity of the waves from a point source at a distance d from the source is i. at what distance from the sources is the intensity equal to 2i

Explanation:

Intensity of the waves from a point source can be given by Power divided by surface area.

For P Power source and at a distance d from source Intensity is given by

when intensity is 2I then it is at a distance of let say d'

Divide 1 and 2 we get

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