In a Young's double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500 nm is used. Ten fringes are observed on the same section of the screen when another light source of wavelength $\lambda$ is used. Then the value of $\lambda$ is (in nm) __________.
Answer (integer)
750
Solution
The length of the screen used portion for 15
fringes, and also for ten fringes
<br><br>15 $\times$ 500 $\times$ ${D \over \lambda }$ = 10 $\times$ ${{\lambda D} \over \lambda }$
<br><br>$\Rightarrow$ 15 × 50 =$\lambda$
<br><br>$\Rightarrow$ $\lambda$ = 750 nm
About this question
Subject: Physics · Chapter: Optics · Topic: Reflection and Mirrors
This question is part of PrepWiser's free JEE Main question bank. 197 more solved questions on Optics are available — start with the harder ones if your accuracy is >70%.