Young’s Double Slit Challenge
25 NEET-standard questions on coherent sources, Young’s double slit, path difference, bright and dark fringes and fringe width. Answer each one. If you get it wrong, Vidya Ma’am explains it with an animated movie you can control, a slider to play with, and a step-by-step solution. Then try again.
NCERT Physics XII Part II · Ch. 10 · pp. 265–266Keys: A–D or 1–4 to answer
🧠 Formula memory tricks (open before you start)
Why Young’s trick worksTwo pinholes lit by the SAME source S: any phase jump hits both, so they stay coherent.Two lamps: random phase, intensities just add
Path differenceS₂P − S₁P ≈ d·y/Dsmall angles
Brighty = nλD/dn = 0, ±1, ±2 … (path difference = nλ)
Darky = (n + ½)λD/dpath difference = (n + ½)λ
Fringe widthβ = λD/dequally spaced; β ∝ λ, ∝ D, ∝ 1/d
In a mediumβ′ = β/nλ → λ/n, frequency unchanged
Counting gapsFrom fringe k to fringe m there are (m − k) gaps.
right first tryfixed after explanationstill to fix
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