Single slit of width a: path difference between its edges is a sin θचौड़ाई a की एकल झिरी: इसके किनारों के बीच पथांतर a sin θSingle slit of width a: path difference between its edges is a sin θ

NCERT Fig 10.14 · Class 12 Physics · Chapter 10 · interactive diagram

Parts and what they mean

• Parallel beam (plane wave) (समांतर किरण पुंज (समतल तरंग)) — Falls normally on the slit, so all points of the slit are secondary sources in phase.
• Single slit LN (एकल झिरी LN) — A narrow opening; M is its midpoint.
• Slit width a (झिरी की चौड़ाई a) — Diffraction is noticeable when a is comparable to a few wavelengths.
• Normal MC (अभिलंब MC) — Line through M perpendicular to the slit plane; it meets the screen at C (θ = 0).
• Rays to P at angle θ (कोण θ पर P तक किरणें) — Lines from L, M, N to a far point P are treated as parallel, all at angle θ to MC.
• Path difference NQ (पथांतर NQ) — Between the two edges: NP − LP = a sin θ ≈ aθ. Minima where aθ = nλ (n = ±1, ±2, …).
• Angle θ (कोण θ) — Direction of P measured from the normal MC.
• Point P on the screen (पर्दे पर बिंदु P) — The contributions of all parts of the slit are added here with their phase differences.
• Centre C (केंद्र C) — All paths equal: central maximum.
• Screen (पर्दा) — Diffraction pattern appears here.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 10.14. Report a mistake