A) \[\frac{3}{2}\]
B) \[\frac{4}{9}\]
C) \[\frac{2}{3}\]
D) \[\frac{9}{4}\]
Correct Answer: D
Solution :
For an isotropic point source of power P, intensity J at a distance r from it is\[I=\frac{P}{4\pi {{r}^{2}}}\] Since power P remains the same, \[\therefore \] \[\frac{{{I}_{1}}}{{{I}_{2}}}={{\left( \frac{{{r}_{2}}}{{{r}_{1}}} \right)}^{2}}={{\left( \frac{9}{4} \right)}^{2}}\] \[\because \] \[I\propto {{A}^{2}}\] where A is the amplitude of a wave \[\therefore \] \[\frac{{{A}_{1}}}{{{A}_{2}}}=\sqrt{\frac{{{I}_{1}}}{{{I}_{2}}}}=\frac{9}{4}\]You need to login to perform this action.
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