PHY2606
Assignment 4 Solutions
Chapter 12
Unique Number: 685128
Due Date: 21st July 2025
, Assignment 4 Solutions
Chapter 12: Waves in Optical Systems
Unique Number: 685128
Due Date: 21st July 2025 at 23:00
Question 1
Problem Statement
Monochromatic light illuminates two slits separated by 1.2 mm, creating an interference
pattern on a screen 3.6 m away. The distance between the third and sixth dark fringes on
the screen is 5.3 mm.
(a) Determine the wavelength of the light.
(b) If the width of each slit is a = 0.15 mm, determine the width of the central diffraction
maximum and the number of interference maxima contained within it.
Step-by-Step Solution
(a) Wavelength Calculation
Position of dark fringes:
1 λL
ym = m +
2 d
Distance between 3rd and 6th dark fringes:
λL λL
∆y = (6 + 12 ) − (3 + 12 )
=3·
d d
1
Assignment 4 Solutions
Chapter 12
Unique Number: 685128
Due Date: 21st July 2025
, Assignment 4 Solutions
Chapter 12: Waves in Optical Systems
Unique Number: 685128
Due Date: 21st July 2025 at 23:00
Question 1
Problem Statement
Monochromatic light illuminates two slits separated by 1.2 mm, creating an interference
pattern on a screen 3.6 m away. The distance between the third and sixth dark fringes on
the screen is 5.3 mm.
(a) Determine the wavelength of the light.
(b) If the width of each slit is a = 0.15 mm, determine the width of the central diffraction
maximum and the number of interference maxima contained within it.
Step-by-Step Solution
(a) Wavelength Calculation
Position of dark fringes:
1 λL
ym = m +
2 d
Distance between 3rd and 6th dark fringes:
λL λL
∆y = (6 + 12 ) − (3 + 12 )
=3·
d d
1
