Optics 6 Question 29
31. Two coherent monochromatic light beams of intensities $I$ and $4 I$ are superposed. The maximum and minimum possible intensities in the resulting beam are
$(1988,1 M)$
(a) $5 I$ and $I$
(b) $5 I$ and $3 I$
(c) $9 I$ and $I$
(d) $9 I$ and $3 I$
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Solution:
- $I _{\text {max }}=\left(\sqrt{I _1}+\sqrt{I _2}\right)^{2}=(\sqrt{4 I}+\sqrt{I})^{2}=9 I$
$I _{\text {min }}=\left(\sqrt{I _1}-\sqrt{I _2}\right)^{2}=(\sqrt{4 I}-\sqrt{I})^{2}=I$
