Physics Discussion Problems 

1. Light of wavelength 600 nm illuminates a double slit with a slit separation of 0.30 mm.  An interference pattern is produced on a screen 2.5 m from the slits.  Calculate the separation of the interference fringes on the screen near the central maximum. (5mm)

2.  Coherent light of wavelength 620 nanometers is incident on a double slit.  The slit separation is .3 mm.  An interference pattern forms on a screen 2 meters from the slits.  a) What is the distance from the central maximum to the 4^th maximum? b) What is the distance from the central maximum to the 5^th minimum?  c) If the whole apparatus were placed underwater would the distances between the maximums and minimum increase, decrease, or stay the same? (1.65 cm, 1.8cm)

3.  In a double-slit experiment, sodium light (l = 589 nm) produces fringes spaced 1.8 mm apart on a screen.  Find the fringe spacing when mercury light (l = 436 nm) is used.  (1.33 mm)

4. A pair of slits is illuminated by blue light (437.5 nm) and an interference pattern is observed where exactly 15 fringes occur in 7.53 cm.  The screen is 1.25 meters from the slits.  Determine the separation of the slits. (.108 mm)

5. Green light of 483.4 nm illuminates a pair of slits that separated by 0.47 millimeters.  The interference pattern is observed on a screen 75 cm from the slits.  Determine the width of the central bright spot (the distance from total darkness on one side to total darkness on the other side). Determine the position center of the 7th bright spot.

(.771 mm; 5.4 mm )

6. Light of wavelength 600 nm illuminates a double slit with a slit separation of 0.30 mm.  An interference pattern is produced on a screen 2.5 m from the slits.  Calculate the separation of the interference fringes on the screen near the central maximum. (5mm)

7.  Coherent light of wavelength 620 nanometers is incident on a double slit.  The slit separation is .3 mm.  An interference pattern forms on a screen 2 meters from the slits.  a) What is the distance from the central maximum to the 4^th maximum? b) What is the distance from the central maximum to the 5^th minimum?  c) If the whole apparatus were placed underwater would the distances between the maximums and minimum increase, decrease, or stay the same? (1.65 cm, 1.8cm)

8.  In a double-slit experiment, sodium light (l = 589 nm) produces fringes spaced 1.8 mm apart on a screen.  Find the fringe spacing when mercury light (l = 436 nm) is used.  (1.33 mm)