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bio website nl.linkedin.com/in/…
location Canada
age 33
visits member for 4 years, 7 months
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Dec
3
comment Deriving the speed of the propagation of a change in the Electromagnetic Field from Maxwell's Equations
If you want to learn more, a good book to read is David J. Griffiths' Introduction to Electrodynamics, chapter 9.
Dec
2
comment Why does my watch act like a mirror under water?
@Frédéric: OK, I'm convinced - as you say, $n\sin\theta$ is the same in each material. What I didn't think of is that if your eye is directly above the watch and the water surface, there is no refraction there, so it's as if you were observing underwater. Also, with more careful observation of my watch, I determined the angle at which it happens was closer to 50 degrees, so this agrees more with the critical angle of 48.7 degrees.
Dec
2
answered An iPhone falling on carpet is fine, is it true?
Dec
2
comment An iPhone falling on carpet is fine, is it true?
I'd bet a lot of money that I could find a height from which falling onto a carpet would damage an iPhone!
Dec
1
comment Why does my watch act like a mirror under water?
I tried it myself. Underwater the faceplate turned opaque at an angle of about 30 degrees like in the original post. I tried to observe the effect in air, but couldn't - I saw Fresnel reflection, but up to an angle of about 80 degrees I could still see the digits under the faceplate at least faintly. I couldn't observe all the way to 90 because the watch housing sticks up around the faceplate a little.
Dec
1
answered Light emission spectrum units
Dec
1
comment Why does my watch act like a mirror under water?
@Frédéric, @Jerry: if the total reflection happens at the glass-air surface, then you don't even need to be underwater to see the effect. I wanted to try some experiments, but I didn't have a watch handy. I'll see if I can find one this evening.
Dec
1
comment Why does my watch act like a mirror under water?
@Jerry: I thought of etalon effects, but as you say, there wouldn't be one critical angle, but several maxima.
Dec
1
comment Why does my watch act like a mirror under water?
Good guess, but you've got your $n$'s mixed up. There is no water-air surface here, because there's glass or plastic (the watchplate) in between the water and the air! The index of plastics and glasses is usually higher than water, so unless this watchplate happens to have $n\approx 1.2$, then there must be something else going on.
Dec
1
awarded  Enthusiast
Dec
1
comment How can you focus sound?
That's actually diffraction, not focusing.
Nov
24
comment How can you focus sound?
As with sound, but I wanted to keep the answer simple ;-)
Nov
24
answered How can you focus sound?
Nov
23
comment How to get the cosine of a waveform?
Do you mean you have a Fourier spectrum of the waveform?
Nov
20
revised How to determine phase angle for a sinusoidal motion?
corrected remark about amplitude
Nov
20
answered How to determine phase angle for a sinusoidal motion?
Nov
18
comment How “How to See Without Your Glasses” works?
Your answer is correct, but I think there's a more intuitive way to explain it.
Nov
18
answered How “How to See Without Your Glasses” works?
Nov
16
comment How can we describe the polarization (of light) coming from an arbitrary angle?
Actually, "p" and "s" are defined with respect to a surface of reflection. As I said, I always mix them up, but as far as I remember, "s" is polarized in the plane of the surface of reflection, and "p" is polarized in the plane defined between the incoming and outgoing beams. So, "s" and "p" are still defined when you reflect a beam upwards.
Nov
16
comment Amount of 2 amperage
@endolith, Because "amperage" has the stereotype clinging to it that it's only used by people who don't know what current or amperes are. Please note I'm not saying that stereotype is necessarily true.