A thin plastic sheet of refractive index text1.6 is used to cover one of the slits, among the two slits, in a double-slit arrangement. The central point on the screen is now occupied by what would have been the 7t h bright fringe before the thin plastic sheet was used. If the wavelength of light is 600 nm , the thickness (in μm ) of the thin plastic sheet is

Question

A thin plastic sheet of refractive index text1.6 is used to cover one of the slits, among the two slits, in a double-slit arrangement. The central point on the screen is now occupied by what would have been the 7t h bright fringe before the thin plastic sheet was used. If the wavelength of light is 600 nm , the thickness (in μm ) of the thin plastic sheet is (A) 7 (B) 4 (C) 8 (D) 6

Tardigrade Admin · Accepted Answer

The change in path =(μ - 1)t . This path length change the position of bright fringe upto seventh bright fringe. t(. μ - 1 .)=7λ t=(7(600 × 10-9)/(1.6-1)) =7× 10- 6m⇒ 7Î¼m

$7$

$4$

$8$

$6$

The change in path $= (μ - 1) t$ . This path length change the position of bright fringe upto seventh bright fringe.
$t (μ - 1) = 7 λ$
$t = \frac{7 ( 600 \times 1 0 ^{- 9} )}{( 1.6 - 1 )}$
$= 7 \times 1 0^{- 6} m \Rightarrow 7 μ m$

7

4

8

6

The change in path =(μ−1)t . This path length change the position of bright fringe upto seventh bright fringe. t(μ−1)=7λ t=(1.6−1)7(600×10−9)​ =7×10−6m⇒7μm

$7$

$4$

$8$

$6$

The change in path $= (μ - 1) t$ . This path length change the position of bright fringe upto seventh bright fringe.
$t (μ - 1) = 7 λ$
$t = \frac{7 ( 600 \times 1 0 ^{- 9} )}{( 1.6 - 1 )}$
$= 7 \times 1 0^{- 6} m \Rightarrow 7 μ m$