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Wave Optics · ব্যতিচার

Two beams of light meet on the screen. Where the path difference is half a wavelength, the bright fringe you would expect turns dark.

The bright bands sit where the path difference is a whole number of wavelengths — there the waves arrive in step and reinforce.

Same light, same screen: the pattern is just the two paths agreeing or disagreeing, fringe by fringe.

Tutor connected

Whiteboard
two paths, ½λ apart= dark fringe

Real capability, recreated here — the tutor speaks and draws in the app.

>নিউটনের গতিসূত্র বুঝিয়ে দাও>Big-O of this recursive function>Organic chemistry: reaction mechanisms>সালোকসংশ্লেষণের আলোক পর্যায়>Turn this lecture sheet into a course>Balance this redox equation, step by step>Prove this by induction>নিউটনের গতিসূত্র বুঝিয়ে দাও>Big-O of this recursive function>Organic chemistry: reaction mechanisms>সালোকসংশ্লেষণের আলোক পর্যায়>Turn this lecture sheet into a course>Balance this redox equation, step by step>Prove this by induction
>আলোর ব্যতিচার — দুটো আলো মিলে অন্ধকার কেন?>Data structures: linked lists vs arrays>মাইক্রোইকোনমিক্স — চাহিদা ও যোগান>ওষুধটা শরীরে কীভাবে কাজ করে?>RC circuit — why the capacitor lags>Bias–variance tradeoff, plainly>আলোর ব্যতিচার — দুটো আলো মিলে অন্ধকার কেন?>Data structures: linked lists vs arrays>মাইক্রোইকোনমিক্স — চাহিদা ও যোগান>ওষুধটা শরীরে কীভাবে কাজ করে?>RC circuit — why the capacitor lags>Bias–variance tradeoff, plainly
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It starts with whatever you're stuck on. Then you say how far to take it — a single answer, or the whole thing from first principles.

>আলোর ব্যতিচার — দুটো আলো মিলে অন্ধকার কেন?
Just answer itOne answerLooked up, answered, sourced. No course built.
The gist3–4 partsThe shape of it, in one sitting.
The whole thing5–7 partsBuilt up from what you already know.
First principles8–12 partsDerived, not asserted — every step worked.
Or upload your own lecture sheet — everything below works on your PDF too.
Research

It reads up first, then teaches you

You've asked. Before it answers, it reads the web properly — five researchers at once, a critic sending thin sections back and you watch it happen.

> আলোর ব্যতিচার — from the beginningRunning
  1. Planning the researchWorking out what has to be looked up
  2. Reading the web5 researchers, in parallel
  3. Laying out the partsTurning the findings into an ordered course
  4. Reviewing the planA critic checks the order, coverage and depth
  5. Writing the courseOne writer per part, all at once
What you get
1Why two waves can cancel
2Huygens' principle, on a diagram
3The double-slit, fringe by fringe
4Path difference and the bright-band rule

Every part ships with the sources it was written from.

Learn

One chapter. Five ways at it.

The course is yours now. Reading it again is only one way in — practise it, see it drawn, or ask the tutor. Click through.

Part 1Part 2Part 3Part 4
Part 2 · The double-slit, fringe by fringe
d·sinθ = mλ

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বাংলা

যে ভাষায় ভাবো, সে ভাষায় শেখো

Taught in Bangla, out loud — while coherent, phase and path difference stay exactly as your book prints them.

Bangla voicesTerms stay in English
From a physics lesson

Coherent দুটো উৎস মানে তাদের phase-এর পার্থক্য সময়ের সাথে বদলায় না। তাই পর্দায় fringe গুলো স্থির থাকে — আর path difference দেখেই বলা যায় কোন বিন্দু উজ্জ্বল, কোনটা অন্ধকার।

↑ Explained in Bangla. Terms held in English on purpose.

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Yes, including out loud. The lesson is written in Bangla and the voice tutor speaks it, while technical terms stay in English — wavelength, phase, coherent — so what you learn matches your textbook, your notes and what you'll write in an exam. Nine tutor voices, each with a Bangla sample you can play before choosing.

A chat reply is one answer to one question, and then it's gone. Porphy runs a research pipeline — a planner splits your topic, five researchers read the web in parallel, a reviewer sends thin sections back and what you get is a whole course in parts with its sources attached, plus MCQs, flashcards, a concept map that scores what you know, and a tutor that will explain any line of it out loud while drawing.

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