No time to read it properly
You need three chapters out of twenty, and the three depend on notation defined in the other seventeen.
For engineers and specialists
The answer is in a 600-page book. The deadline is Friday.
Upload the monograph, the manual or the standard everyone cites. Get the chapters you need as lectures at the depth you choose, with the examples taken from your own work.
- Choose pages or chapters
- Your own examples
- Listen on the commute
Déposez votre livre ici
EPUB, FB2, PDF, DjVu ou TXT, jusqu’à 200 Mo
Votre fichier reste privé
What gets in the way
Written for another decade
The classic of the field uses terms, units and examples nobody on your team has met.
A summary is not enough
A page of bullet points tells you what the book concludes, not why, and you have to defend the why in a review.
What changes
The depth you choose
An hour-long overview of the whole book to find what matters, then the chapters that matter with every formula kept and explained.
Examples from your own work
Tell it what you build or measure. A lens formula is then explained on your camera, a control loop on your machine.
Terms defined once, used the same way
The whole text is read before the first lecture is written, so a thing keeps one name through the course, and each part knows what the earlier ones explained.
Figures and formulas read from the page
For a PDF or a scan, the pages with figures, tables and formulas are looked at as images, so what the text extraction lost still reaches the lecture.
Lisez, regardez ou écoutez
Combinez voix, dessins et texte à votre guise. Changez quand vous voulez.
ExplaintedPhotographic Optics
VoixImagesTexte
A thin lens forming an image
The first thing to know about a lens is how hard it bends light. Hold a magnifying glass in the sun: the rays arrive side by side, leave it leaning towards one another, and a little way behind the glass they meet in a bright dot. The distance from the glass to that dot is the focal length, and nearly everything else about the lens follows from it.
A lens is stronger when its glass is denser and its surfaces are more curved. Take ordinary glass, in which light travels one and a half times slower than in air, and curve both sides like a ball twenty centimetres across. Work it through and the focal length comes out at about ten centimetres: sunlight gathers into a point a palm's width behind the lens.
The book writes this as a formula, and we will come to it in a moment. It says no more than what we have just seen: denser glass or more curved surfaces, and the focal length gets shorter.
IntroductionPartie 1 sur 17
1:238:22
1×
Introduction
A thin lens forming an image
The distance from the glass to that dot is the focal length, and nearly everything else about the lens follows from it.
A lens is stronger when its glass is denser and its surfaces are more curved.
1:238:22
1×
How to set it up
- 1
Start with "Big picture"
The whole book in about an hour. Enough to decide which chapters deserve the full treatment.
- 2
Then the chapters, with formulas
Choose the chapters and "Formulas explained" or "Formulas in words". You see the price before anything is made.
- 3
Say what you work on
One sentence about your field in "Your own examples" changes every example in the course.
Find out in an hour what the book says
Upload it and listen to the free sample before paying for anything.
Upload the bookQuestions
Can I rely on it for a design decision?
Use it to understand the book, and take the numbers you will rely on from the book itself. The lectures are AI-generated; each part is checked against its passage and corrected, which lowers the error rate and does not make it zero.
Does it handle scans and old books?
Scanned PDF and DjVu files are recognised, and pages with figures and formulas are also read as images. Very poor scans come out worse; the free sample shows what your file gives.
Can I take the audio with me?
Yes. With a studio voice a course can be downloaded as MP3, and as MP4 with the drawings.
Also for
Students
The textbook the course is built on, at a level you can follow tonight.
See howResearchers
Read into the neighbouring field without losing a month to its textbook.
See howTeachers
See a hard chapter explained five ways before you explain it yourself.
See howCurious readers
The great hard books you always meant to read, finally followed to the end.
See how