Recent content by Antti

  1. A

    Question about surface area of faraday cage

    No size does not matter, although I don't know about ridiculously large cages. There are big cages for sale and for example at CERN they routinely enclose big objects in tin foil or similar material. It's the quality of the seal that matters.
  2. A

    Why does eg a falling stone crate many ripples on a water surface?

    Thanks, that sort of makes sense. But he might say "well why doesn't the center return to its original state just once and only create one ripple?". Somehow I suspect energy conservation has something to do with it.
  3. A

    Why does eg a falling stone crate many ripples on a water surface?

    So I've studied physics at the university quite a bit and was a bit surprised when I couldn't answer this simple question a friend asked me. When something lands in water why are several ripples created? Like why is the resulting water wave made up of several peaks and valleys and not just one...
  4. A

    Could dark matter be invisible bound states of ordinary matter or ehm, aliens?

    I've thought about dark matter and I'm wondering if it could possible be made up invisible bouond states of ordinary matter? Wikipedia says "According to consensus among cosmologists, dark matter is composed primarily of a new, not yet characterized, type of subatomic particle." But why a...
  5. A

    Heat capacity of a solid using the Einstein model

    Homework Statement Plot the heat capacity as a function of temperature for aluminium, using the Einstein model. Homework Equations The Einstein model for heat capacity: The Attempt at a Solution The model assumes that the frequencies of all the harmonic oscillators in the material are...
  6. A

    Understanding Dumbbell Rotation: Laws and Material Constants

    Well no. Say I had a dumbbell made entirely of Copper and I knew the exact shape of the whole thing. Then I'm thinking there should be some torsion-spring effect, though small, in the middle bar when I apply a torque to one end. No materials are perfectly rigid. How do you calculate this from...
  7. A

    Mathematical shape for a lens with no spherical aberration

    Im no expert on this, but I do know that aspheric lenses are used in high-end camera objectives http://en.wikipedia.org/wiki/Aspheric_lens But as you may know, no lens can be perfect for all wavelengths.
  8. A

    Understanding Dumbbell Rotation: Laws and Material Constants

    I just thought about a dumbbell (for some reason) and how one end rotates if I turn the other. If it was just a "mathematical system" with two flat cylinders and a long cylinder in between, then one end would rotate in exactly the same way as the other. But if the middle bar was rubber for...
  9. A

    Man dies in Black Friday shopping stampede.

    But also cheap stuff ;) Everything's great when it's cheap...
  10. A

    Fishing Science: Is There Evidence That Supports Fishing Methods?

    My dad is an enthusiastic fisherman. He goes fly fishing almost every weekend of the year and of course I join him sometimes. Many things he and his friends say and believe about different lures, weather etc often sound like hasty conclusions. So I'm wondering if there are any scientific studies...
  11. A

    Why Do Some People Enjoy Holiday Shopping Despite the Stress?

    Personally I think Christmas should be replaced with "surprise day". An international commitee would each year come up with a new purpose, theme and execution of surprise day. This information will be released to the public exactly three days (this is very important) before commencing...
  12. A

    Lingusitics EU Progress: Official Language Change to "Euro-English

    If you want any force in your swearing then try finnish :) I think the whole world needs to have the same language
  13. A

    Entropy change with identical and different gases

    Homework Statement There's a thermally insulated container with a removable wall. So there are two compartments inside, one with volume V (i call it left box) and the other with volume V + B (right box) so the total volume is 2V + B. Both boxes have N molecules of an ideal gas and are in...
  14. A

    Auger-effect, photoelectron energy

    I see. Well that obviously raises the question about how they got the answer in the book. I think you can understand that I'd rather trust the authors than you ;)
  15. A

    Auger-effect, photoelectron energy

    Okay, seems like my crappy first post is no longer editable... EDIT: fixed! :) Gokul: The book gives both the kinetic energy and velocity of the electron in the answer. I have only compared the first value since the velocity can't turn out right if the kinetic energy is wrong. So my answer...
Back
Top