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Science fair electromagnet suggestions

Instock

Mar 5, 2024
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My kid is working on an electromagnet science fair project. Basically, he's going to wrap wire around stuff and see what works best. I don't want to the science part for him, but he needs help with the logistics, materials, and safety. We have no experience with this stuff.

What are some cool things that we should put in his hands? What should we use for a power source? Batteries? USB? 12V? How can we control the current? Indicator lamp? Wire nuts? I dunno. Not sure what questions to ask, but hit me with some stuff the a 10yo kid could impress his friends with. I can solder if I absolutely have to, but it'll be ugly!
 

Bluejets

Oct 5, 2014
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Electromagnet, use a relay stripped down.

It won't lift much but will show the principle if the armature and spring are left intact.
 

Instock

Mar 5, 2024
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Electromagnet, use a relay stripped down.

It won't lift much but will show the principle if the armature and spring are left intact.
Interesting idea. That could definitely be one of them.

How do we power it? I have a 12v, 3 amp power souce from a car radio store that closed. I also have a Bluetti solar generator battery that can give me 12v, 10 amps, as well as USB ports. My dad wants to donate a model train transformer and we can do it with AC? I have a power supply for jumping my car that has USB. Or just keep it simple with a lantern battery or some AA alkalines in a holder?
 

Bluejets

Oct 5, 2014
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Simple battery is best for kids, safe, portable (if using AA cells in a battery case/holder). Voltage of relay to match close to battery. i.e. 4 AA (6v) is ok for 5 or 6v relay....plus it suits Vin to Adruino uC which I'm sure the kid would be more interested in for control of infinite number of devices.
Just don't be surprised if they leave you in their dust trail.

Word of warning...do not use 9v smoke alarm battery.....except in smoke alarm or maybe your multimeter....you have bought the kid a multimeter I take it. Plenty of videos on how to use basics and cheap as...just don' t go testing anything mains level....
 

Delta Prime

Jul 29, 2020
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I bought this one for my little booger blasters.
Shop around. Use only as reference please...
If nothing else it'll give you a proper safe idea!
 
Last edited:

danadak

Feb 19, 2021
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Regards, Dana.
 

Instock

Mar 5, 2024
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I'd love to give them a way to watch the current, but my old Meyer says to not hook it up for more than 15 seconds. We already blew the fuse once. Could I use one of those clamp meters or....?
 

Instock

Mar 5, 2024
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Yeah, it seems like only the most super-expensive meters have dc on the clamp.

I bought a little 10 amp analog meter, but I think the resistance of the meter itself is too much when my only load is a coil of wire?
 

Instock

Mar 5, 2024
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It seems like I actually get more current by putting batteries in parallel than in series. I would have bet money that putting them in series would increase the voltage and thereby increase the current. It seems like putting them in series does increase the voltage, but that is countered by the increase in internal resistance. The total current doesn't change much. If, however, I put them parallel, the voltage stays the same while the effective internal resistance goes down. The current increases! At least that's my explanation so far. Thoughts?
 

Delta Prime

Jul 29, 2020
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The total current doesn't change much. If, however, I put them parallel, the voltage stays the same while the effective internal resistance goes down
You were doing really good! Until effective internal resistance. I can see why but you can't think of the effective internal resistance like that, it's going to confuse the heck out of you.
When you combine two electrochemical cell's
you get what is called a battery.
Internal resistance of a battery is the electronic resistance plus the ionic resistance.
This is called " total effective resistance" of a battery.
The electronic resistance is dependent upon the alloys used for the positive & negative terminals.
Ionic resistance, is the resistance to current flow within the battery & this is dependent upon the chemistry of the battery, electrolyte conductivity, ion mobility & electrode surface area.
And all of this has to do with battery current capacity.The charge of a battery can only be seen (measured) when it's connected to a load & that is depended on battery chemistry, depth of discharge, drain rate & the age of the battery can impact internal resistance during discharge.

 

Martaine2005

May 12, 2015
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In series, the voltage adds up and parallel the current adds up.
Example: 2 x 12V batteries @ 100 Amps each wired in series = 24V @ 100 Amps.
2 x 12V @ 100 Amps each wired in parallel = 12V @ 200 Amps.
Read the link that @Delta Prime gave above.

Martin
 
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