2,788 reputation
1325
bio website nl.linkedin.com/in/…
location Canada
age 33
visits member for 4 years, 10 months
seen 6 hours ago

Dec
15
awarded  Enlightened
Dec
15
awarded  Nice Answer
Dec
11
awarded  Nice Answer
Dec
11
awarded  Quorum
Dec
8
comment Is there a travelling speed of for electric field? If yes, what is it?
possible duplicate of Is electricity instantaneous?
Dec
8
comment Is there a travelling speed of for electric field? If yes, what is it?
Are you sure that photons travel through the wire? If the current is DC, then the frequency of these photons is 0, and so according to $E=\hbar\omega$ they have no energy? I always thought that it was just a disturbance in the electric field.
Dec
8
comment Is there a travelling speed of for electric field? If yes, what is it?
Huh? So even the one-meter wire would cause the bulb to light 2 hours and 47 minutes after you flip the switch?
Dec
7
comment Why does dust stick to rotating fan propeller?
Fans can often be found in kitchens, which makes them even more likely to be sticky with oil. Maybe not your fan, but I'm sure this explanation accounts for at least half the dust found on fan blades!
Dec
7
comment Theoretical Physics - How to?
Looking back on my answer, I see you might have interpreted it as saying that a theorist had to be an excellent experimenter too - I've edited it to say what I really meant, which is just that it's important not to ignore experimenting.
Dec
7
revised Theoretical Physics - How to?
edited to clarify intent
Dec
6
answered Theoretical Physics - How to?
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.