---
title: 'new course : beyond'
---

! *YOUR  CHALLENGE*   :   
!
! *CHALLENGE n°1* : The enigma of the cup of ice cream.
!
! ![](defi_glace_650.jpg)
! 
! Why does the volume of the cup seem to be completely filled with ice cream, when it contains so little?
!
! <details markdown=1>
! <summary>
! I choose this challenge.
! </summary>
! Information : the refractive index of the air is $n_1=1$, the one for the cup is $n_2=1.5$. a $R_1$ is the inner radius of the cup, $R_2$ its outer radius.
!
! _Don’t look at the answer, take some time to think, a few days if necessary. The time to build your mental representation of the phenomenon, to formulate it in words is important, a thousand times more important than the ephemeral moment of reading the few words of the solution._
! 
! <details markdown=1>
! <summary>
! CLUE 1 : keywords
! </summary>
! angle of total reflection.
! </details>
! <details markdown=1>
! <summary>
! CLUE 2  : trail
! </summary>
! The colored ray that reaches the eye of the observer comes from a point of the strawberry ice cream located at the interface with the inner wall of the glass cup.
! </details>
! <details markdown=1>
! <summary>
! ANSWER
! </summary>
! to write
! </details>
! </details>
!
! -----------
!
! *CHALLENGE n°2* : Automatic rain detector
!
! ![](detecteur_pluie_650.jpg)
!
! How to detect the rain on a windshield, the detection system being inside the car?
!
! <details markdown=1>
! <summary>
! I choose this challenge
! </summary>
! Information : the refractive indices of air, water and glass of the windshield are respectively $n_ {air} = 1$, $n_ {glass} = 1.5$ and $n_ {water} = 1.33$. The detection system includes a diode light emitter and then a light detector, both attached to the windshield on the inside of the car. The light emitted by the diode propagates in the windshield.
!
! _Don’t look at the answer, take some time to think, a few days if necessary. The time to build your mental representation of the phenomenon, to formulate it in words is important, a thousand times more important than the ephemeral moment of reading the few words of the solution._
!
! <details markdown=1>
! <summary>
! CLUE 1 : keywords
! </summary>
! total reflection angle
! </details>
! <details markdown=1>
! <summary>
! CLUE 2 : trail
! </summary>
! Both the light emitter and the light receiver are in contact with the windshield inside the car. The refractive interface of the windshield on the outside of the car is a glass-air refracting surface if it does not rain, and a glass-water refracting surface if there is a drop of water.
! </details>
! <details markdown=1>
! <summary>
! ANSWER
! </summary>
! to write
! </details>
! </details>
!
! -----------
!
! *CHALLENGE n°3* : A multi touch screen technology (challenge under construction)
!
! -----------
!
! *CHALLENGE n°4* : Luminous fountain (challenge under construction)
!


!!!! *DIFFICULT POINT* (contribute, or indicate a difficult point of understanding)
!!!!

!! *BEYOND* (to contribute)
!!

!! *CULTURAL POINT* (contributor)
!!

!!! *DO  YOU  MASTER ?*
!!! <details markdown=1>
!!! <Summary>
!!! Describe the test
!!! </summary>
!!! The text of the test (and its images, figures, audio, video, etc ...)
!!!
!!! Question text
!!! <details markdown=1>
!!! <summary>
!!! Answer choice 1
!!! </summary>
!!! Text if this answer 1 is chosen
!!! </details>
!!! <details markdown=1>
!!! <summary>
!!! Answer choice 2
!!! </summary>
!!! Text if this answer 2 is chosen
!!! </details>
!!! <!--possibility to add answers, questions-->
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!!! <details markdown=1>
!!! <summary>
!!! Complete solution.
!!! </summary>
!!! text of the solution
!!! </details>
