science project question

I am figuring with all the nerds here, somebody will be able to answer this.


my son made a telegraph for his 4th grade science project. battery, copper wire, nail, paperclips for both the botton and the "tapper".

here's the problem - when he closes the circuit, the paper clip sticks to the nail and doesn't disengage. if we move it farther away, the paper clip comes close to the nail but doesn't touch it. I am thinking that there has to be a better materail to use. tried weakening the magnet, tried moving the paperclip around.


any ideas from all the various nerds and engineers out there (and I mean that in the most respctful way possible)?

Off the top of my head, once you close the circuit, it wants to stay closed. The trick is fixing the two elements in place, strong enough to withstand the force needed to break the circuit.

The paperclips don't have enough elasticity. If you have a spring (maybe from an old toy or remote control) use that with some other ferrous metal attached to the end above the paper. It will resist deformity and metal fatigue and keep the 'printer' functioning for a long time.

thanks, yeah, I am trying to figure out what kind of spring to use. J sent me a link to a plan that uses a "spring" made of a pie plate, we might try that. any additional ideas are welcome

There are also a lot of household plastics that are highly elastic (something like a plastic fork tine should do). Just sitting here at my desk I have a plastic pen clip, the ink well from the inside of the pen, and a book binder that would all work. Again, just attach a ferrous metal to the end and it should work well.