Question 227: Wave Optics

Question

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) __________.

Accepted Answer

The length of the screen used portion for 15
fringes, and also for ten fringes
15 $ 	imes $ 500 $ 	imes $ ${D \over \lambda }$ = 10 $ 	imes $ ${{\lambda D} \over \lambda }$
$ \Rightarrow $ 15 ÃÂ 50 =$\lambda $
$ \Rightarrow $ $\lambda $ = 750 nm

Wave Optics

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) __________.

Integer / Numeric Answer Type