In an interference experiment, third bright fringe is obtained at a point on the screen with a light of 700 nm. What should be the wavelength of the light in order to obtain 5th bright fringe at the same point ?

Question

In an interference experiment, third bright fringe is obtained at a point on the screen with a light of 700 nm. What should be the wavelength of the light in order to obtain 5th bright fringe at the same point ? (A) 500 nm (B) 630 nm (C) 750 nm (D) 420 nm

Tardigrade Admin · Accepted Answer

3rd max. of λ1=5th max. of λ2 (3 λ1 D / d )=(5 λ2 D / d ) ⇒ λ2=(3/5)(700)=420 nm

Q. In an interference experiment, third bright fringe is obtained at a point on the screen with a light of $700 nm$ . What should be the wavelength of the light in order to obtain $5^{t h}$ bright fringe at the same point ?

500 nm

630 nm

750 nm

420 nm

$3^{r d} max$ . of $λ_{1} = 5^{t h} max$ . of $λ_{2}$
$\frac{3 λ _{1} D}{d} = \frac{5 λ _{2} D}{d}$
$\Rightarrow λ_{2} = \frac{3}{5} (700) = 420 nm$

Q. In an interference experiment, third bright fringe is obtained at a point on the screen with a light of 700nm. What should be the wavelength of the light in order to obtain 5th bright fringe at the same point ?