Diffraction

In our experiment, our main colour is green, but we also used red and blue lasers. Our diffraction grating had 300 lines per millimetre, therefore d=3330 nm.

Green laser

Order of fringe n Left angle l (°) 0 10 20.5 31.5 45 59 87 Right angle r (°) Uncertainty in the angle (°) 1 1.5 1 1 1 1.5 3

0 0 1 -10.5 2 -20 3 -30 4 -40.5 5 -55 6 -72.5 Wave length stated on laser: 533.2 nm

Red laser

Order of fringe n 0 1 2 3 4 5 Wave length stated on laser: 657 nm 0 -12 -25 -38.5 -55 -83 Left angle l (°) 0 12 25 38.5 55 84 Right angle r (°)

Blue laser

Order of fringe n 0 0 1 -7.5 2 -15 3 -23 4 -31 5 -40 6 -50 7 -62.5 8 -81.5 Wave length stated on laser: 406.6 nm Left angle l (°) 0 7.5 15 23 31 46 50 61.5 80 Right angle r (°)

Wave lengths on graph

The different coloured triangles represent their respective laser, fx. the blue blue triangles represent the blue laser. The graph is d×Sin , where d is 3330 nm and is the average angle of the different angles is calculated by ( L+ r)/2. As an example, for the green laser, the third dot s left angle was 30° and its right dot was 31.5°, so the average is (30+31.5)/2=30.75, for d×Sin it is then 3330×Sin(30.75)= 1702.606. The slope represents the wave length for the various lasers, to calculate it, we take =568 nm. , again using the third green dot,