Recent content by Cool4Kat

So, I was looking into Einstein's 1907 paper where he derived the specific heat of solids using quantum mechanics and I found that Einstein just took the derivative of Planck's equation from 1900 for the average energy, U, as a function of time (and multiplied it by 3N for the three dimensions)...

That was what I was taught as well, but the "relatively cool" thing doesn't work with lamp light going through sodium flames. The sodium is relatively hot, not cold (possibly hotter than the lamp but definitely hotter than the surrounding air). Also, the sodium is still yellow if viewed from...

So I was taught in school that heated low density gases produce spectral lines and cool low density gases absorb their spectral lines. I mentioned this to my husband and he asked me what the definition of hot and cool were and I had no idea. The more I thought about it, the more confused I...

<Moderator's note: Merged from another thread.> It seems pretty clear that when a core electron is ejected and another electron falls into that hole, it can either release that energy in a photon or in ejecting another electron. That makes plenty of sense to me. What I can't understand is why...

Thank you so much for replying. I really appreciate it.

Thank you so much. I was actually interested because of the history of the x-ray and the x-ray machine. I have two follow up questions: 1. Does the bremsstahlung have to do with the density *or* the charge of the nucleus? Or, is that basically the same thing? 2. Do you know why lighter...

i know that x-rays are produced when a beam of high energy electrons hits a metal anode but why does that work better than when that same beam hits glass (like in the Crookes tube)? Thanks

Thank you! That makes a lot more sense.

Thank you everyone who has replied *so much* for taking the time to help me. I thought that the LO energy was at twice the frequency, but it sounds like the LO was half the frequency making the antenna tuned circuit to be at the second harmonic (that makes so much more sense!). So, to put in...

Hi, I was wondering if any of you fine people can help me understand a few things about Howard Armstrong and Harry Houke's superhet radio receiver built in 1924. My fist question is that they used a second harmonic and I don't understand why. Where was the second harmonic used and how did it...

What’s the name of the app??

I followed Tom's advice and looked up the specs for a phone this is what I got: I found the specs for the iPhone4 (admittedly a little behind the times but that is OK). It's battery is 3.7 Volts and has a capacity of 1400mAh. It would provide 14 hours of phone and 10 hours of wifi. So that...

I am doing a series of videos on the history of electricity and I am working on a video on Volta and the first battery. Anyway, I want to compare the voltaic pile to a typical li-ion battery running my iPhone. Now the voltaic pile could easily create 20 V of potential but it had high...

I read an article that said that they were produced since 1946 (in a Scientific American from 1948) however, Marty Cooper complained that his battery weighed 1 pound. 10 years later, the whole system weighed 1 pound so his battery must have gotten significantly smaller. Thanks

I think your mistake is that the height is not 2.6 m, the length of the wedge is 2.6 meters. So the potential energy is mgh but you have the wrong h! (However, you can use trigonometry to find the height given the angle and the length of the wedge) Now if you want to use the Work =...