Diffraction 5 Pound Note

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    • #44942
      Profile photo of Andrew Normand

      This is the interference pattern from a laser beam through Canadian dollar’s diffraction grating

      Canadian dollar 1


      I learnt of the Canadian dollar diffraction from Steve Mould’s YouTube channel

      I would recommend sharing Steve’s channel with all physics students. You can follow Steve on Twitter https://twitter.com/MouldS

      Here is the Canadian dollar diffraction video

      I tried a laser through the new 5 pound note

      diffraction 5 pound

      You can see the queen is made of little plastic dots on clear plastic
      Queen 2The region that I got the best diffraction from was under the Queen’s chin and you can see the ordered spacing that created it here

      chin china me 2

    • #44943
      Profile photo of Andrew Normand

      it’s rubbish isn’t it compared to the Canadian one? I was very disappointed when I tried it. Will be sticking to Canadian notes for demos.

    • #44991
      Profile photo of Andrew Normand

      Where did you get the $ sign from? Where did you have to shine the laser on? When I did it on my Canadian $5 note I got something closer to the new £5 note.


    • #44999
      Profile photo of Andrew Normand

      Hi Alessio, I shone the laser through clear maple leaf is. The blue dot in the dollar below.
      Canadian security dollar

      The dollar I had is in the IOP Electromagnetic Workshop box and was a shown at the East Midlands day. I seem to remember that I could see no dollar pattern and was convinced that it is a true diffraction pattern. When I get hold of one again I will use my dino-light microscope to have a look. In the pictures above I used the dino-light to magnify the £5 pound note enough to see the little blobs of plastic.

      It is a definite security feature on the Canadian money and an interesting website is here.

      Where with the £5 note the diffraction pattern we see is just from the periodic structure of the plastic blobs

    • #45001
      Profile photo of Andrew Normand

      Thanks, someone shared this link in PTNC that shows how the new £5 notes work well to play an LP record 🙂 pretty cool too.

      • #45003
        Profile photo of Andrew Normand

        Somehow I don’t think my partner is going to be impressed if I try to use a fiver to play one of his treasured vinyls.

      • #45004
        Profile photo of Andrew Normand

        I just looked at a $20 note, the pattern in the dot looks like a very complicated maze, the type you get in puzzle books with right angled corners.

    • #48023
      Profile photo of Andrew Normand

      I did have a go at making a sound with the new 5 pound note. It did scratch the record a little

    • #48397
      Profile photo of Andrew Normand

      Just got my first new 10 pound note. Still waiting to shine a laser through it.

      Shining UV on it is quite uneventful really

      crown 10 pound note

      I do like the new iridescence as a security feature.

      bank note 5

      My daughter pointed out how much how the crown looks like a face

    • #48404
      Profile photo of Andrew Normand

      It’s great that the BoE is celebrating diversity like that!

    • #49258
      Profile photo of Andrew Normand

      I have just come across a plastic Australian 5 dollar bank note. No interesting diffraction to report yet.

      The iridescence on the bird is amazing and I got from blue through green to red by rotating through an angle.

    • #49262
      Profile photo of Andrew Normand

      Nice one Dave,

      the Queen’s chin in the new £5 is quite interesting though. I often get students to find the spacing between the dots by measuring the diffraction pattern.

      lovely real application.

      • #49264
        Profile photo of Andrew Normand

        I’ve tried to get teachers interested in using diffraction to measure things, like the spacing on a DVD but they don’t appear to see the benefit (it isn’t in the curriculum)

        I bid on an interferometer on ebay once but was the under bidder. I think finding uses for these formulae helps to embed the principles and broaden the understanding.

    • #64464
      Profile photo of Andrew Normand

      An interesting feature of the old 5 pound note was the infrared security feature.

      Using a cheap webcam with the IR filter removed. If you shine an IR LED and block the visible light entering the camera. Then on the note you only see half the Queen’s face. I have been told it works on the new £20 but have not tried it yet.

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