NUST NET Physics — Physical Optics
Physical Optics is part of the FSc Physics course that NUST NET-Engineering draws on (Physics is 60 of the 200 MCQs). It breaks into 3 subtopics, and we hold 64 NET-pattern practice MCQs on it, each with a written explanation. Tap a subtopic below to practise just that.
Subtopics (3)
How Physical Optics is tested
Across the 8 NET-pattern papers on ParhaiKrlo, Physical Optics accounts for 24 questions. It appears in all 8, about 3 questions a paper. The heaviest was NUST NET Past Paper 07, with 3 questions.
| Paper | Questions |
|---|---|
| NUST NET Past Paper 07 | 3 |
| NUST NET Past Paper 08 | 3 |
| NUST NET Past Paper 05 | 3 |
| NUST NET Past Paper 06 | 3 |
| NUST NET Past Paper 03 | 3 |
| NUST NET Past Paper 04 | 3 |
| NUST NET Past Paper 01 | 3 |
| NUST NET Past Paper 02 | 3 |
Physical Optics MCQs from the NET-pattern papers
Try each one before opening the answer. Each comes with a short explanation.
- Q1 · NUST NET Past Paper 07 · Physical Optics
In Young's double-slit experiment, if the separation between the slits is increased, the fringe spacing:
- A.decreases
- B.increases
- C.stays the same
- D.becomes infinite
Show answer
Answer: A. decreases — Fringe spacing Δy = λL/d, so a larger d gives narrower fringes.
- Q2 · NUST NET Past Paper 08 · Physical Optics
In Young's experiment with light of wavelength 600 nm, the path difference at the third bright fringe (not counting the central one) is:
- A.1500 nm
- B.1800 nm
- C.900 nm
- D.600 nm
Show answer
Answer: B. 1800 nm — The nth bright fringe has path difference nλ = 3 × 600 = 1800 nm.
- Q3 · NUST NET Past Paper 05 · Physical Optics
In Young's double-slit experiment the fringe width is 0.4 mm. If the slit separation is halved (everything else unchanged), the fringe width becomes:
- A.0.2 mm
- B.1.6 mm
- C.0.8 mm
- D.0.4 mm
Show answer
Answer: C. 0.8 mm — Fringe width β = λD/d ∝ 1/d; halving d doubles β to 0.8 mm.