Recent content by spf

Dear Rozy94, did you find out why your two electromagnets were always attracting each other? If yes, please tell us, it's really interesting! Thanks.

Yes. Yes. The reason for both is Maxwell-Faraday's law: a time-varying magnetic field creates an electric field. http://en.wikipedia.org/wiki/Maxwell_Laws#Faraday.27s_law http://en.wikipedia.org/wiki/Faraday%27s_law_of_induction#Maxwell.E2.80.93Faraday_equation

Another idea: did you check that both batteries are working correctly? If one of them didn't work, you would only have one electromagnet and one simple bolt, and they would behave exactly as you described: attract each other in each configuration. (They same applies if the wire is contacted...

Yes. If you like, just replace "atom" by "lattice point" everywhere in my previous post.

This is interesting... Have you tried out all the possibilities? Let's say magnet A has the ends A1 & A2 and magnet 2 has the ends B1 & B2. Did you try out ALL the following possibilities:"A1 to B1", "A1 to B2", "A2 to B1" and "A2 to B2" WITHOUT disconnecting the battery when turning the magnet...

Atoms on the sides are shared between two unit cells, so you can only count each one as 1/2 atom. Atoms on the edges are shared four unit cells, so they count as 1/4 atoms. Atoms on the corners are shared between eight unit cells, so they count as 1/8 atoms. Do the numbers add up now?

OK, up to now I tried many things to figure it out, have redone this calculation many times, rechecked the values and have tried out three different sets of coordinates of the A, B, A' and B' atoms in the unit cell and I always get the same result. I went the other way round by asking myself...

Glad that I could help. Thanks to Ray Vickson for the elegant alternative substitution and to Karamata for the nice visual presentation of the solutions with wolfram-alpha.

The electrons cannot flow from the metal to the valence band of the semiconductor because the valence band of the semiconductor is full. It's a n-type semiconductor, so it has an excess of electrons and thus electrons in the conduction band but no holes in the valence band. In case you meant...

The only difference to part 1 of the question is that now the speed of the block at the top of the hill is not 6 m/s but... how much?

Glad to help.

The following link should be helpful: http://en.wikipedia.org/wiki/Complex_number#Conjugation

Glad to help.

At the beginning, the whole energy of the system is in the elastic energy of the spring. When the block is at the top of the hill, the energy is in the potential energy of the block and the kinetic energy of the block. Thus, it's NOT the potential energy which equals the sum of the elastic...

Finding the two conditions for y/x is only the first step in solving the original equations. With this step you did not find the solutions to the original equations yet, you just narrowed them down. By now, you only know that the solutions to the original two equations satisfy either y=x or...