Stuck on one line?Make it click.
Ask one question, build the whole course, or bring your own slides and notes into a project. Then learn it with a voice tutor and whiteboard, in বাংলা or English, at 2am, as many times as you need.
Fringe width β depends on…
the colour of the screenλ, D and dthe brightnessPoint at the line. Hear it explained.
Not a chatbot reading an answer aloud. A tutor with a voice and a pen, working on the exact sentence you pointed at.
Highlight the line
Select the sentence you are stuck on, in a course Porphy wrote or in your own PDF. That one line is the whole question.
Hear it, in your language
A real-time voice session opens on that line, in Bangla or English, with technical terms kept in English so it matches your book. 9 voices. Cut in whenever you like.
Watch it drawn
It draws on a whiteboard beside the text while it talks: the axes, the waves, the step you missed. Some things are not explainable in prose.
Lock it in
Ask for flashcards, an MCQ set or a visual on what you just fumbled, and it makes them without hanging up. After about a minute of silence it ends the call, so it never meters while you read.
পর্দায় দুটো আলোর রশ্মি মিলছে। যেখানে path difference অর্ধেক wavelength, সেখানে উজ্জ্বল fringe-এর বদলে অন্ধকার দেখা যায়।
তাই dark fringe-এর শর্ত: path difference হবে অর্ধেক wavelength-এর বিজোড় গুণিতক।
Slit দুটো কাছাকাছি আনলে (d কমালে) বা পর্দা আরও দূরে সরালে (D বাড়ালে) fringe গুলো চওড়া হয়:
এটা কাজ করে শুধু coherent উৎসে। দুটো উৎসের phase-এর পার্থক্য বারবার বদলালে ডোরাগুলো মুছে যায়, পর্দায় কোনো স্থির pattern তৈরি হয় না।
λ = 600 nm আলো d = 0.3 mm দূরত্বের দুটো slit পেরিয়ে D = 1 m দূরের পর্দায় পড়ছে। তাহলে β = (600 × 10⁻⁹ × 1) / (0.3 × 10⁻³) = 2 mm।
One question. Two ways forward.
Get a sourced answer, or turn the topic into a course. Have your own slides and notes instead? Put them in a Project. You choose the shape before Porphy starts.
Snap the page you're stuck on.
Photograph your notes, the board or a textbook page and ask about it, handwriting included. Turn on Exam paper and every question on a past paper gets answered, in order, sized to its marks.
Question ১(ক)
[১ নম্বর]
দুটি coherent উৎস থেকে আসা আলো মিলে কোথাও উজ্জ্বল, কোথাও অন্ধকার ডোরা তৈরি করাকে আলোর ব্যতিচার বলে।
Why: “coherent উৎস” আর “উজ্জ্বল–অন্ধকার ডোরা”, এই দুটো কথাতেই নম্বর।
Question ১(খ)
[২ নম্বর]
ডোরার প্রস্থ β = λD / d। পর্দা দূরে সরালে D বাড়ে, তাই ডোরা চওড়া হয়; চিড় দুটো কাছে আনলে d কমে, তাতেও ডোরা চওড়া হয়।
Why: সূত্রটা লেখা আর দুটো পরিবর্তনের ফল বলা, দুই নম্বরের দুটো ধাপ।
↑ In the paper's order, each answer sized to its marks, a line for one mark, the working for more.
Don't trust the answer. Follow the evidence.
Porphy can research a topic and teach it as a course, with the sources attached. Or put your own slides, chapters and notes into a Project and ask across all of them, every answer points to a page.
Course research
আলোর ব্যতিচার · standard depth
- Plan the questionsBreak the topic into what must be proved
- Read across the web5 researchers work in parallel
- Challenge weak coverageA critic sends thin sections back
- Write every partOne writer per part, all at once
Project
Physics · Semester 2 · 3 materials
- lecture-10.pptxSlides
- Chapter 4, Optics.pdfPDF
- class-notes.docxWord
Where do slit width and fringe spacing connect?
Fringe spacing grows as the slits move closer together.
Study guide across every material, each topic with its pages.
Concept map of what you know, in Projects only.
A quote Porphy cannot find in your files is shown as text, never as a link to a page.
A course is only the beginning.
Read on the left. Open the tool you need on the right, visualize the idea, practise it, or ask about this exact chapter.
Read
Your chapter, part by part, the tutor one highlight away.
যে ভাষায় ভাবো, সে ভাষায় শেখো
Taught in Bangla, out loud, while coherent, phase and path difference stay exactly as your book prints them.
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.
Your first 2,000 credits are on us
Now the cost. Not a seven-day trial, a real budget, no card, and it never expires.
A month of studying, roughly
1,700 of 2,000 credits- 1 full courseresearched, in parts, with sources900
- 12 minutes with the voice tutorthe lines you're actually stuck on480
- 10 MCQ sets & flashcard decksgenerated from your own chapter200
- 40 questions about a chapterask the same thing five ways120
All of that, and 300 credits are still sitting there , another 100 questions, whenever you need them. No card, and they never expire.
If you run out
Top up whenever, or don't. No monthly fee, nothing to cancel, and credits are metered at the AI provider's own list price with nothing added on top.
Free accounts run a lighter pipeline so the free credits stretch: 2 web searches per topic, up to 3 parts, 2 photos per question, and text and tables instead of generated visuals.
Before you sign up
Almost certainly. It isn't tied to a syllabus, it researches whatever topic you give it, at whatever depth you ask for. School science, a university algorithms course, a professional exam, a semester of lecture slides you're trying to get through: a chapter your teacher skipped and a topic that isn't in any textbook work the same way.
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 sample you can play before choosing. English works the same way, voice included, and a tutor call stays in the language you chose for the whole call.
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, visualizations, a chat that stays on your chapter, and a tutor that will explain any line of it out loud while drawing.
Nothing, until you decide to top up. There is no monthly fee, no card kept on file and nothing to cancel, an empty balance just means the AI features pause. When you want more, credits are metered at the AI provider's own list price with nothing added on top, and every call is itemised on your usage page so you can see exactly where they went.
Yes, lecture slides, a chapter, a lab manual, a past paper, as a PDF, PowerPoint, Word, Markdown or plain-text file. The study tools work on it as they do on a researched course: highlight a line for the voice tutor, generate MCQs and flashcards from it, visualize an idea, or ask questions about it in chat. One limit worth knowing: an uploaded PDF has to contain real text, so a scanned book won't open in the reader. For a photo of a page, attach it to your question instead, see the next answer.
Yes. Attach photos to your question, handwritten notes, the board, a page of your textbook, and ask about them. Porphy reads them as pictures, so handwriting and diagrams count, and the answer builds on what's on your page: explaining it, correcting a mistake in it, filling in what it skips. You can attach up to 5 photos and one PDF to a question (2 photos on a free account). Each photo is checked first: if it doesn't look like study material, a selfie, a landscape, you get a warning and can remove it or use it anyway before anything starts.
Yes, attach the question paper as photos or a PDF, choose Answer, and set the style to Exam paper. Every question on it is answered in the paper's order, numbered the way the paper numbers it, and each answer is sized to the marks printed beside it: one line for a 1-mark question, the working and a diagram or formula where a bigger one needs it. Every answer ends with a line on what earns those marks, so it doubles as revision. A question it can't read is listed as not answered rather than guessed at.
A Project is for a whole subject at once: put a semester's slides, chapters and class notes (PDF, PowerPoint, Word, Markdown or text) in one place. You can then ask questions across all of them and get answers that point to the material and page they came from, build one study guide over everything, and see a concept map of what you know. A quote Porphy cannot find in your files is shown as plain text and never as a link to a page. The concept map lives in Projects only; a course or a one-off answer does not have one. Porphy does not go looking for papers for you, a Project holds what you bring.
That's your choice, and both paths exist on purpose. Answer mode looks a question up and answers it, useful the night before an exam. Course mode asks what you already know first, then teaches from that point up. The practice tools push the other way: Live Tutor mode makes you explain the concept back in your own words and tells you what you left out.
Every part of a course ships with the sources it was written from, so you can check any claim against the original. A critic agent reviews the plan and sends thin sections back for another research pass before you ever see them, and you can ask for any section to be rewritten, expanded or explained more simply.
Open the chapter you've been avoiding.
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