Two independent lamps are incoherent: intensities just add, no fringesदो स्वतंत्र लैंप कला-असंबद्ध हैं: तीव्रताएँ बस जुड़ती हैं, कोई फ्रिंज नहींTwo independent lamps are incoherent: intensities just add, no fringes
NCERT Fig 10.11 · Class 12 Physics · Chapter 10 · interactive diagram
Read Chapter 10 with this diagramइस डायग्राम के साथ अध्याय 10 पढ़ेंIs diagram ke saath Ch 10 padhiyeAll Physics diagramsसभी भौतिकी डायग्रामSaare Physics diagrams
Parts and what they mean
- Two separate sodium lamps (दो अलग सोडियम लैंप) — Light from an ordinary source changes phase abruptly in about 10⁻¹⁰ s, so two lamps never keep a fixed phase relation.
- Opaque screen (अपारदर्शी पर्दा) — Holds the two pinholes.
- Pinholes S₁, S₂ (पिनहोल S₁, S₂) — Each is lit by a different lamp, so S₁ and S₂ are incoherent sources.
- Overlapping light (अतिव्यापी प्रकाश) — The phase difference changes very rapidly, so only the time-average is seen.
- Screen: no fringes (पर्दा: कोई फ्रिंज नहीं) — Average of cos²(φ/2) is ½, so I = 4I₀ × ½ = 2I₀ everywhere — the intensities simply add.
Original diagram drawn by Simple Learning Hub, based on NCERT Fig 10.11. Report a mistake