Question

7 pts Question 10 Light of wavelength 575 nm passes through a double-slit and the third order bright fringe is seen at an angle of 3.5 away from the central fringe. What is the separation between the double slits? O 18 m 33 pm 38 m 28 m 23 um Question 11 7 pts A slit of width 0.010 mm has light of frequency 7.5x 1014 Hz passing through it onto a screen 60 crn away. How wide is the central maximum? (c 3.00 x 108 m/s) 1.8cm O 0.12 cm 2.4 cm 4.8 cm 0.90 cm

Answer 1

unit of wavelength = 575 nm passes through a double slit their order is seen at 3.5 Now, for double slit the integer ancy pattern looks something like this The distance between central maxima and third order things is 3 beta, when beta is the fringe width. Now we know beta = lambda D/d when D is distance of scream from slit and d is separation of slit lambda is wavelength. Now applying basic trigonometry. Now, subsisting the value tan?(3.5) = 3 beta/D theta tan(3.5) = 3 lambda D/d times D or d = 3 lambda/x tan (3.5) = 3 times 575 times 10^-9 m/16.349 = 2.82 times 10^-3 = 28 mu m Given Slit width (d) = 0.010 mm = 10^-2 mm = 10^-5 m Frequency (r) = 7.5 times 10^14 Hz Distance of screen with sud (D) = 60 cm = 0.6 m width of control maxima can be calculated using the fact that the position for minimum can be calculated using d sin theta = m lambda