In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation of 7.2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes' separation of 8.1 mm. The wavelength of second light is nm.

Question

In a Young's double slit experiment, a laser light of 560 nm produces an interference pattern with consecutive bright fringes' separation of 7.2 mm. Now another light is used to produce an interference pattern with consecutive bright fringes' separation of 8.1 mm. The wavelength of second light is nm. (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

β propto λ λ2=(9/8) λ1 ∴ β2=(9/8) β1=(9/8) × 560=630 nm

β∝λ λ2​=89​λ1​ ∴β2​=89​β1​=89​×560=630nm

$β \propto λ$
$λ_{2} = \frac{9}{8} λ_{1}$
$∴ β_{2} = \frac{9}{8} β_{1} = \frac{9}{8} \times 560 = 630 nm$