Science Buddies: "Ask an Expert"

Just wondering, for a science project we are following the "Shaking Up Some Energy" at this link:

https://www.sciencebuddies.org/mentorin ... l?from=TSW

We can get the light to blink, but not stay lit. Do you know why this would be? Any info. would be helpful.

Hi,
Does it blink at the same tempo as the shaking? Is it possible that the led is lighting as the magnet is passing through the coils, and then goes out when the magnet is beyond the coils?
Chris

No, shake it 50 times blinks at most blinks 28 times with 3 of neodymium magnets together. I attached a pdf file of a graph of our tests with 30 ga wire. Possible our magnets are not strong enough? Does not really say size to use, just says small powerful.

Dear gmitch,

Your device is working just fine.  The blinking or strobing is related to the difference between AC and DC circuits.  The generator you built makes AC current.  When the magnet moves through the coil in one direction the electrons are pushed one way, when the magnet moves back through the coil the electrons move the other way.  The LED is a diode and can only conduct electricity in one direction. The light only emits when the current is flowing in the forward direction.  This is unlike a regular light bulb filament which heats up and emits light when electricity flows both ways.  Batteries generate DC current.  When an LED is connected to a DC circuit it will emit light all the time (or never if hooked up backwards).  The generator you built is also different from the shaker flashlights shown on the project idea site.  The flashlights use a shaking magnet coil to charge a battery which then powers the LED.

What is unclear to me from the information you provided is why the generator only blinked a few times with the weaker magnets.  I believe, however, that the weaker magnets did not create enough current to power the LED each time it passed through the coil.

Additional information about shaking magnet coil generators and LED can be found in the published journal version of the experiment listed in the Credits at the end of the "Shaking up some Energy" site and at a site containing instructions for a similar experiment at:

webapps.Isu.umich.edu/physics/demolab/DisplayexpFile.aspx?fileid=6

My daughter is trying this experiment but we can not get the light to work. We have gone over evrything and the only thing I see is the wire we have is 22 gauge would this matter?

Thanks

No, i dont think it matters(: