Question 127: Wave Optics

Question

In a Young’s double slit experiment, 16 fringes
are observed in a certain segment of the
screen when light of a wavelength 700 nm is
used. If the wavelength of light is changed to
400 nm, the number of fringes observed in the
same segment of the screen would be

Accepted Answer

Let the length of segment is "$$l$$"
Let N is the no. of fringes in "$$l$$"
and w is fringe width.
$$ 	herefore $$ Nw = $$l$$
$$ \Rightarrow $$ N$$\left( {{{\lambda D} \over d}} ight)$$ = $$l$$
As in both cases segment length is same.
$$ 	herefore $$ $${{{{N_1}{\lambda _1}D} \over d} = l}$$
and $${{{{N_2}{\lambda _2}D} \over d} = l}$$
$$ 	herefore $$ $${{{{N_1}{\lambda _1}D} \over d}}$$ = $${{{{N_2}{\lambda _2}D} \over d}}$$
$$ \Rightarrow $$ $${{N_1}{\lambda _1}}$$ = $${{N_2}{\lambda _2}}$$
$$ \Rightarrow $$ 16 ÃÂ 700 = N
2
ÃÂ 400
$$ \Rightarrow $$ N
2
= 28

Answer

28

Answer

24

Answer

30

Answer

18

Wave Optics

In a Young’s double slit experiment, 16 fringes are observed in a certain segment of the screen when light of a wavelength 700 nm is used. If the wavelength of light is changed to 400 nm, the number of fringes observed in the same segment of the screen would be

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