Wave Optics Question 11
Question 11 - 2024 (31 Jan Shift 1)
Two waves of intensity ratio 1:9 cross each other at a point. The resultant intensities at the point, when (a)
Waves are incoherent is $I _1(b)$ Waves are coherent is $I _2$ and differ in phase by $60^{\circ}$. If $\frac{l _1}{l _2}=\frac{10}{x}$ then $x=$
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Answer: (13)
Solution:
For incoherent wave $I _1=I _A+I _B \Rightarrow I _1=I _0+9 I _0$
$I _1=10 I _0$
For coherent wave $I _2=I _A+I _B+2 \sqrt{I _A I _B} \cos 60^{\circ}$
$I _2=I _0+9 I _0+2 \sqrt{9 I _0^{2}} \cdot \frac{1}{2}=13 I _0$
$\frac{I _1}{I _2}=\frac{10}{13}$
