Practice Section
Timed practice: Easy → Moderate → Advanced
⏱ Practice Timer
Recommended: 15 minutes for Easy, 20 for Moderate, 25 for Advanced
Easy Level Practice Problems
Problem 1
In YDSE, distance between slits d = 0.4 mm, distance to screen D = 1.5 m, wavelength λ = 600 nm. Calculate the fringe width β.
Problem 2
State the conditions necessary for obtaining sustained interference of light.
Problem 3
In single slit diffraction, if slit width is increased, what happens to the width of central maximum?
Problem 4
Light of intensity I₀ passes through a polaroid. What is the intensity of transmitted light?
Problem 5
What is Brewster's angle for glass of refractive index 1.5?
Moderate Level Practice Problems
Problem 1
In YDSE with D = 1 m, d = 0.5 mm, a thin glass plate (μ = 1.5, thickness = 10 μm) is introduced in front of one slit. By how many fringes does the pattern shift? (λ = 500 nm)
Problem 2
Two slits separated by 0.2 mm are illuminated by light of wavelength 500 nm. If interference pattern is observed on screen 2 m away, find the position of 3rd dark fringe from center.
Problem 3
In YDSE, intensities of two sources are in ratio 9:4. Find ratio of maximum to minimum intensity in interference pattern.
Advanced Level Practice Problems
Problem 1
In YDSE, entire apparatus is immersed in liquid of refractive index n. If air is now slowly introduced into a slab of thickness t in front of one of the slits, how many fringes will cross a fixed point on the screen?
Problem 2
Show that average intensity over many fringes in an interference pattern equals I₁ + I₂, proving energy conservation.