Question

5. A pair of narrow, parallel slits separated by 0.200 mm are illuminated by green light (a 546.1 nm). The interference pattern is observed on a screen 1.20 m away from the plane of the parallel slits. Calculate the distance between the first and second dark fringes in the interference pattern. a) 2.62 mm b) 2.18 mm c) 3.88 mm d) 4.37 mm e) 3.28 mm

Answer 1

here,

the seperation between the slits , d = 0.2 mm = 2 * 10^-4 m

wavelength , lamda = 546.1 nm = 546.1 * 10^-9 m

screen distance , D = 1.2 m

the distance between the first and second dark fringe in the interference pattern , y = lamda * D/d

y = 546.1 * 10^-9 * 1.2 /(2 * 10^-4) m

y = 327.66 * 10^-5 m = 3.28 * 10^-3 m

y = 3.28 mm

the distance between the first and second dark fringe in the interference pattern is e) 3.28 mm