Results 1 to 9 of 9

Math Help - Totally internally reflected

  1. #1
    Member
    Joined
    Nov 2009
    Posts
    94

    Totally internally reflected

    Hi
    I am looking for a good website. I need practice with drawing refracted rays and totally internally refracted rays. This will also include critical angles.

    Please recommend any useful websites. It will be wonderfully appreciated. The exam is on Monday.

    Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by gbenguse78 View Post
    Hi
    I am looking for a good website. I need practice with drawing refracted rays and totally internally refracted rays. This will also include critical angles.

    Please recommend any useful websites. It will be wonderfully appreciated. The exam is on Monday.

    Thanks.
    Did you try using Google?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Nov 2009
    Posts
    94
    Yes. Most of the websites are information based. I have the textbook' Nelson' Physics and their is not much information on how to draw them. I have also considered the past questions and the answers are written, not demonstrated. So, at a loss really. Its very difficult because I study independently.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
    From
    Mauritius
    Posts
    1,260
    If it's drawing, you should know how to precisely draw any angle given the normal and the reflecting/refractive surface, knowing where the light will bend the more when refraction is concerned.

    The critical angle is often required for you to work out, given the incident angle and the refractive index between the two media involved.

    You could post some of your questions (one at a time) and post what you tried to do. We'll help you know whether you are correct or not, what you have to change/improve, etc.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Nov 2009
    Posts
    94
    Thanks. I dont know how to sketch on the forum. How do I do that?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor Unknown008's Avatar
    Joined
    May 2010
    From
    Mauritius
    Posts
    1,260
    Hm... the simplest way to do this is to have your sketch as an image (scanned, or created through paint of another graphic program you are familiar with). If you can have grids in your image, they'll greatly help. Then you upload it on the site and attach it to your posts, or you upload it on an image hosting site and post the link. If on top of that you can measure angles, it'll be awesome!
    Follow Math Help Forum on Facebook and Google+

  7. #7
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    When it comes to total internal reflection and refraction then you'd do well to remember Snell's Law

    n_1 \sin\theta _i = n_2 \sin\theta _r where:

    • n_1 = Refractive index of the incident material (the material it's leaving)
    • n_2 = Refractive index of the material it's entering
    • \theta _i = incident angle
    • \theta _r = refracted angle


    The critical angle is when \theta _r = \frac{\pi}{2} = 90^{\circ}

    \theta _c = \arcsin \left(\dfrac{n_2}{n_1}\right)

    For incident values above this total internal reflection occurs (and it's always the same angle as the incident so you draw a perpendicular and sketch the same angle)
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by e^(i*pi) View Post
    When it comes to total internal reflection and refraction then you'd do well to remember Snell's Law

    n_1 \sin\theta _i = n_2 \sin\theta _r where:

    • n_1 = Refractive index of the incident material (the material it's leaving)
    • n_2 = Refractive index of the material it's entering
    • \theta _i = incident angle
    • \theta _r = refracted angle
    The critical angle is when \theta _r = \frac{\pi}{2} = 90^{\circ}

    \theta _c = \arcsin \left(\dfrac{n_2}{n_1}\right)

    For incident values above this total internal reflection occurs (and it's always the same angle as the incident so you draw a perpendicular and sketch the same angle)
    All of which is readily found using Google (which was the point of post #2).

    Quote Originally Posted by gbenguse78 View Post
    Yes. Most of the websites are information based. I have the textbook' Nelson' Physics and their is not much information on how to draw them. I have also considered the past questions and the answers are written, not demonstrated. So, at a loss really. Its very difficult because I study independently.
    There is plenty to be found using Google!! And you can always refer to other textbooks (library is a good start).
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Senior Member
    Joined
    Dec 2010
    Posts
    470
    First page found by Google typing "reflection refraction flash"

    Reflection and Refraction
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Totally internally reflected ray
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: January 17th 2011, 02:40 AM
  2. A point reflected over a line?
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 23rd 2010, 04:15 AM
  3. equation of a reflected line
    Posted in the Geometry Forum
    Replies: 8
    Last Post: May 27th 2010, 09:17 AM
  4. circles touching internally/area...
    Posted in the Geometry Forum
    Replies: 2
    Last Post: February 21st 2010, 10:45 AM
  5. incident and reflected waves
    Posted in the Calculus Forum
    Replies: 3
    Last Post: February 15th 2009, 01:26 PM

Search Tags


/mathhelpforum @mathhelpforum