Science Buddies: "Ask an Expert"

if using more than one magnet (joined together), will it make the light brighter the project is from science buddy's and it is called shaking up some energy

Hi lukedenison,

Welcome to the forum!

I'm not sure what project you're doing. If it's a Science Buddies project idea, could you post a link to it? If not, can you describe what you're doing?

Amanda

http://sciencebuddies.com/science-fair- ... Q&from=TSW
if using more than one magnet(joined together) does it make the light brighter???

Hi lukedenison,
I merged your two topics so that the experts could better understand your project question. In the future, please keep new posts in the same topic using the "post reply" button.
Thanks,
Chris

The voltage that is created in response to the magnet's motion actually occurs in response to a change in the magnetic flux density, which is basically the concentration of magnetic field lines perpendicular to the rings formed by sections of wire. This process is called induction and is described by Faraday's law.

http://en.wikipedia.org/wiki/Magnetic_field (look at the iron filings on the right)
http://en.wikipedia.org/wiki/Faraday%27 ... _induction.

In a very long magnet, the magnetic flux density is close to constant throughout the length of it, but it changes rapidly at the poles -- the lines have to bend around to go through the opposite pole. So if you think about it, the loops of wire that are experiencing the fastest change in flux density (and therefore greatest induced voltage) are those near the ends of the magnets.

Two identical magnets stacked together behave very similarly to one longer magnet. And one longer magnet still has only two ends. So I wouldn't expect the induced voltage to change very much -- perhaps a little because (1) the curvature of the field lines will be slightly different and (2) it might be hard to maintain exactly the same shaking rate if the longer magnet is much closer to the total length of the tube.

The SB experiment is based on this, which is worth reading to help understand induction:

http://www.creative-science.org.uk/gensimple1.html

If you want to change the voltage induced, I would suggest changing either the rate of shaking or the strength of the magnet -- that is, using a weak magnet and then a strong magnet and comparing the results. You could measure the rate of shaking by counting the number of shakes over 10 seconds or so. A metronome or pieces of music with constant beats that you can hear easily might help you keep up a constant pace.

Amanda

Instead of putting a North pole of one magnet next to a South pole of a second identical magnet so they attract to make a larger magnet and reduce the magnetic flux density, try taping two magents together such that the same poles are together and they are repelling. In this case, the magnetic field will be much stronger where the two magnets are repelling each other and you should get an increase in the power generated in a coil around these moving magnets.