Assertion A: For light diverging from a point | vedclass

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(D) The intensity $I$ of light from a point source is given by $I = \frac{P}{A} = \frac{P}{4 \pi r^2}$,where $P$ is the power of the source and $r$ is

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$A$ is false but $R$ is true.

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(D) The intensity $I$ of light from a point source is given by $I = \frac{P}{A} = \frac{P}{4 \pi r^2}$,where $P$ is the power of the source and $r$ is the distance from the source. Since $I \propto \frac{1}{r^2}$,the intensity depends on the distance $r$. Therefore,Assertion $A$ is false. For a point source,the wavefronts are spherical because the light travels at the same speed in all directions,forming a sphere of radius $r$ at time $t$. Therefore,Reason $R$ is true.

Assertion $A$: For light diverging from a point source,the intensity at the wavefront does not depend on the distance.
Reason $R$: In a diverging beam of light from a point source,a spherical wavefront is observed.

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Assertion $A$: For light diverging from a point source,the intensity at the wavefront does not depend on the distance. Reason $R$: In a diverging beam of light from a point source,a spherical wavefront is observed.