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Thank you Jaden for the heads up. I have now uploaded the correct video for Lecture 4.6.

I have from arduino kit, laser 6mm. Its have a 91 Ом, 5% nominal resistor SMD910 direct to. And SMD103 from "one of the three, in pin". SMD or not doesn't matter just for information.

Hello Ahlam, yes, you do have pressure inside of you. With your open mouth, nose, and ears, atmospheric pressure gets inside your body creating an internal pressure that counteracts the outside pressure. Therefore, the net pressure change acting on you is zero, and you do not feel atmospheric pressure.

Yeah, I was wondering about that too. X seems to be the path length difference between Radio wave A and radio wave B. It seems to me that x is the location of the first node in respects to radio antenna B.

By what you are saying, you are talking about Huygens wavelets at the slit. The number of "point sources" or wavelets depends on which minima you are talking about. Assuming you understand what I just wrote, this is the basic process: • Break-up the slit width into equal intervals with secondary wavelets. For the first minima (n = 1) you break it into 3 wavelets which form two pairs; second minima (n = 2) you break it into 5 wavelets which form four pairs; third minima (n = 3) you break it into 7 wavelets which form six pairs; etc. • When all of the pairs of wavelets destructively interfere, then on derives the path difference equations 𝛥r = asin𝜃 = n𝜆, where n = 1, 2, 3, ...

The bending of the wave around obstacles causes them to spread out past small openings. When part of the wave is cut off by some obstacle, we observe diffraction effects that result from interference of the remaining parts of the wave fronts. There is no magnetic attraction of the wave to the obstacle! In fact, the magnetic part of the wave effectively does not interact with the obstacle magnetically (at optical frequencies), but it does electrically.

To describe the difference between the two can become very abstract but the Fendt applet (Reflection and Refraction of Light Waves explained by Huygens' Principle) visually does a beautiful job of showing you. In essence, a "stationary" oscillator is a source that produces little waves called wavelets. When a large collection of "stationary" oscillators are in phase, the sum of all these little wavelets will produce a wave. Again, the applet will show this.

Think of an ocean wave, it has width and height, as it moves perpendicular to the direction of motion. The light wave we talk about in interference and diffraction are plane waves (search Wikipedia for a plane wave and look at the image) that are "rectangular planes" moving towards the slit. So, the horizontal part is diffracted vertically while the vertical part is diffracted horizontally.

Based on what we know of trig functions, sin and cos vary from -1 to 1, but can never equal more than 1. So we can't make an equation where we equate sin(theta) to something greater than 1, it would be mathematical nonsense.

I think what happened is when he multiplied the ∆r by (2π/lamda), it cancels the lambda term and you should end up with phi = (2m+1)π instead of (m+1)π . That would make sense for how you get the odd terms. That's the only thing I can figure.

Ollie is correct. I dropped the factor of 2 in that expression. Without it, one cannot get odd pi values.

It looks like I dropped that term. It should read Acos(φ/2)sin(kx−ωt+φ/2). Thanks for cleaning up my messes!

I was a mistake and as you just stated, it should of been k = 2π/λ

Ones eye perceives the source of light to be an object coming from behind the lens even though there is no object there (the eye is playing a trick on you). For a virtual image produced by a converging lens, there is essentially no light there because most of the light is refracted through the glass with a small amount of light being reflected off of one of its surface.