How can you see this pattern over here like this? So, the 1st wave from this 1st hole. There and then darkness and then another dot and then darkness and another dot and you'll see this continue out much further You'll get, you really will just get, a dot right So if these are all DĪpart, what happens is on the wall over here, instead of getting this smudgy pattern, I'm going to make 1,000's of these holes extremely close togetherĪs long as they're all at distance D apart, something magical happens. So you come over to here and if these are spaced to distanceĭ, I'm just going to make another hole at distance D and then I'm going to make another hole at distance D and then I'm going to make another hole at distance D. So, my question is, is there a better way? Is there a way to make these spots more defined and so youĬan see more of them so they're brighter and the answer is definitively yes and we figured out how to do it and the way you do it, is you just make more holes. Sometimes you're lucky to even see the 5th or 6th bright spot down the line. Probably want to measure distance between two of these bright spots because that's what I can see but because they're smudgy, it's like is that the center? Is this the center? Sometimes the lights not so strong and it's hard to tell and what's worse is these kind of die off and so there's another problem. Side of the triangle and then I would also You'd have these bright spots but they'd kind of blend in to dark spots which blend into bright spots which is why when we draw a graphical representation of this, it kind of looks like this, where these spots are blending into each other which is cool but it also kind of sucks because if you were to go actually try to do this experiment, you'd want to measure some angles and that means that you'd have to measure some distances. Green laser through here what you'd see on the screen would be something like this. Double slits are cool because they show definitively that light can have wave like interference patterns and if you shine a The part of the wave that would reach the point would be near zero if represented in the wavy way, and the latter would have reached the point having being shifted more than π times. For example the wave that was 1.3 shifted from the first ( and still only 1.1 shifted from the previous) and the one that was 1.8 shifted would destroy each other as the former would be shifted to near a the zero point, i.e. What I mean is each light wave emerging from the slit was 1.1 wavelengths shifted compared to the previous ( just as in the constructive point you had each light wave being 1 wavelength shifted compared to the other) * and therefore, over a large number of light waves from the many slits, we had each wave cancelling out with the other*. Considering it s slightly more, as in the example David gave in the video, just as in double slit the light coming from one slit was slightly less constructive ( in the example we just set it to be skewed by 1.1 wavelengths), the light in this case coming from every slit was a little lesser constructive compared to the previous. Here's how: We know from double slit that as you move away from the constructive point the path length difference or ∆x is not exactly 1λ but is slightly more or slightly less. ⇒ As the wavelength of light increases, the central maximum becomes wider.Oh so you're getting stuck on how exactly as we move away from the constructive point do waves get destructive. the start of the first minimum) occurs at an angle given by the following formula: ⇒ The width of the central maximum depends on the wavelength of the light and the slit width ⇒ The dark fringes in between ( minima) are due to destructive inteference ⇒ These bright fringes ( called maxima) are due to constructive interference Note, the reason there is such interference patterns with a single slit is due to the Huygens-Fresnel principle, which states that every point on a wavefront is a source of wavelets (i.e.⇒ When light diffracts though a single slit, a fringe pattern on a screen can be seen with a central bright fringe and less bright fringes each side ⇒ Visible light has an extremely short wavelength so diffraction is only significant if the slit is very narrow
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