JEE PYQ: Wave Optics Question 24
Question 24 - 2019 (08 Apr Shift 1)
In an interference experiment the ratio of amplitudes of coherent waves is $\frac{a_1}{a_2} = \frac{1}{3}$. The ratio of maximum and minimum intensities of fringes will be :
(1) 2
(2) 18
(3) 4
(4) 9
Show Answer
Answer: (3)
Solution
Given amplitude ratio of waves is $\frac{a_1}{a_2} = \frac{1}{3}$
$\frac{I_{\max}}{I_{\min}} = \left(\frac{a_1 + a_2}{a_2 - a_1}\right)^2$
$= \left(\frac{\frac{a_1}{a_2} + 1}{\frac{a_1}{a_2} - 1}\right)^2 = \left(\frac{\frac{1}{3} + 1}{\frac{1}{3} - 1}\right)^2 = \left(\frac{4}{2}\right)^2 = \frac{4}{1} = 4$
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