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NEET
Exam
NEET
Subject
Physics
Chapter
Wave Optics

NEET · Physics · Wave Optics

Assertion A : For light diverging from a point source, the...

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

Options

  1. A(A) and (R) are true and (R) is the correct explanation of (A).
  2. BBoth (A) and (R) are true, but (R) is not the correct explanation of (A).
  3. C(A) is true but (R) is false
  4. D(A) is false but (R) is true.

Correct answer

D. (A) is false but (R) is true.

Step-by-step solution

We have I=EAt=E(4πr2)t∝1r2I=\frac{E}{A t}=\frac{E}{\left(4 \pi r^2\right) t} \propto \frac{1}{r^2} So, intensity depends on distance ⇒\Rightarrow (A) is false and, for diverging beam wavefront is spherical as shown So (R)(\mathrm{R}) is true.
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