It explains light as a wave phenomenon and covers interference, diffraction, and polarization — concepts which ray optics alone can’t explain.
Why oily roads show rainbow colors? It’s wave interference!
Superposition of two light waves results in brighter (constructive) and darker (destructive) regions.
PYQ Type: Interference concept MCQ
Formula for Fringe Width (β).
Where:
PYQ Type: Formula or reasoning MCQ
Requirements for interference to occur.
PYQ Type: AAI loves theory MCQs on this
The bending of light around the corners of an obstacle or slit.
Fact: Diffraction is significant when slit width ≈ wavelength.
PYQ Type: Concept MCQ
The phenomenon of restricting vibrations of light waves to one plane.
Used only for transverse waves (like light)
Why polarized sunglasses cut glare? They block horizontal light waves.
PYQ Type: Polarization definition / application MCQ
Year Question Asked
2021 Shift 2: Polarization property
2022 Shift 3: YDSE fringe width formula
2023 Feb Shift 1: Interference condition MCQ
| Concept | Formula |
|---|---|
| Fringe width (β) | \( \beta = \frac{\lambda D}{d} \) |
| Max path difference (constructive) | \( n \lambda \) |
| Min path difference (destructive) | \( \frac{(2n-1) \lambda}{2} \) |
| Concept | GenZ Example |
|---|---|
| Interference | Oil film colors on water |
| YDSE | Ripple patterns in pond |
| Diffraction | Light bends around door edges |
| Polarization | Polarized sunglasses reduce glare |
Focus Areas:
Q1. Wave optics deals with:
a) Light as particle
b) Light as wave
c) Reflection only
d) None
Ans: b
Q2. YDSE fringe width formula is:
a) \( \frac{\lambda D}{d} \)
b) \( \frac{d D}{\lambda} \)
c) \( \frac{\lambda d}{D} \)
d) \( \frac{d D \lambda}{d} \)
Ans: a
Q3. Interference occurs when two sources are:
a) Coherent
b) Same color
c) Different frequency
d) Random
Ans: a
Q4. Diffraction occurs when slit width is:
a) Much larger than λ
b) Equal to λ
c) Zero
d) None
Ans: b
Q5. Polarization can occur in:
a) Longitudinal waves
b) Transverse waves
c) Both
d) None
Ans: b
Q6. Path difference for constructive interference is:
a) \( \frac{(2n-1) \lambda}{2} \)
b) \( n \lambda \)
c) 0
d) None
Ans: b
Q7. Fringe width is directly proportional to:
a) Wavelength
b) Distance between slits
c) Slit separation (d)
d) None
Ans: a
Q8. The purpose of YDSE is to demonstrate:
a) Reflection
b) Interference
c) Refraction
d) Polarization
Ans: b
Q9. Which optical phenomenon proves light is transverse?
a) Reflection
b) Refraction
c) Polarization
d) Interference
Ans: c
Q10. Unit of fringe width is:
a) Meter
b) Tesla
c) Henry
d) Coulomb
Ans: a