00:01
All right, so let's say there's a diffraction grading that you have with 400 lines per millimeter.
00:09
And so that corresponds to a slit spacing that is one over in in the appropriate unit.
00:16
So 400 lines per millimeter is 400 ,000 lines per meter.
00:21
So our slit spacing is 2 .5 micrometers.
00:25
And our detection screen is 1 .8 meters from the diffraction grading and the location of the first maximum is 33 .1 centimeters.
00:39
So our angle is going to be the inverse tangent of y over l.
00:44
So 0 .331 divided by 1 .8.
00:47
Take the inverse tangent.
00:49
That's about 10 .42 degrees.
00:51
And so our wavelength is just going to be d times the sign of that angle.
00:58
So this should be about 452 nanometers.
01:07
And that's part a.
01:09
Hoygens principle just states that the light emitted from a slit is going to be emitted in spherical waveforms as it travels outwards from the slit.
01:18
And so if we look at kind of a diagram where we pick some angle here, the path -link difference of our slits.
01:25
Width is a between one side of the slit and the other side is approximately we'll call this delta r is approximately basically a sine theta or the path length difference between two slits or between like the center point and the halfway point is going to be a over two sine theta and this should be equal to like a half multiple of the way length for constructive or destructive interference for like a minima so we have a sine theta equals like m times lambda...