Science Buddies: "Ask an Expert"

I want to use an electromagnet in a project , but it is not working.

I created this project two years ago and I want to use it again. At that time, I connected seven 1.5 V batteries and it worked all good. But, carrying around 7 batteries was a difficult task and the batteries dried up quickly. So this time I decided to power it with 9 V batteries, but it didn't worked.

I have wrapped 4-5 layers of insulated copper wire on an iron nail (about 2.5 inches long) and tried connecting it with up to 3 batteries of 9 volts each. Though current is present in the wire (I checked it with a LED), still it is not attracting any metal object, not even a small safety pin.
A 9 V battery may supply less current, but still if current is flowing, it must attract something.

Please help me with this and tell me where am I doing it wrong.

Thanks in advance.

9V batteries will supply less current than AA or larger 1.5V batteries, but they should easily have enough power to run an electromagnet.

1) When you say you wrapped 4 or 5 layers around a nail, did you wrap the layers all in the same direction? Are they even and not haphazard?

2) When you connected the 3 batteries, how did you do that?

3) How did you check for current with an LED? An LED by itself can only handle 1.7 (or perhaps 3) volts, so if you did that without a proper current limiting resistor and didn't fry the LED, you don't have much more than a couple of volts - and that's weird.

You'll need to offer up more information about what you did and how you did it so that we can help you.

9V batteries will supply less current than AA or larger 1.5V batteries, but they should easily have enough power to run an electromagnet.

1) When you say you wrapped 4 or 5 layers around a nail, did you wrap the layers all in the same direction? Are they even and not haphazard?

2) When you connected the 3 batteries, how did you do that?

3) How did you check for current with an LED? An LED by itself can only handle 1.7 (or perhaps 3) volts, so if you did that without a proper current limiting resistor and didn't fry the LED, you don't have much more than a couple of volts - and that's weird.

You'll need to offer up more information about what you did and how you did it so that we can help you.

Thanks for your quick response.

1) What do you mean by same direction? Up/Down or clockwise/anticlockwise.

All layers are in clockwise direction. I don't think up/ down direction will make any difference. But, still I wrapped the layers from down to up and again down.

2) They are connected in series. (Positive of one battery joined to negative of another.)

3) Yes, there is a resistor attached in series with the LED. But, I didn't connect it in the main circuit.

Here's a couple of websites that offer up instructions on making a working magnet.

https://www.sciencebuddies.org/science- ... p035.shtml

http://www.sciencebob.com/experiments/electromagnet.php

The instructions and materials in ours ( the first one) is going to make a stronger magnet than the second.

3 9V batteries in series will give you 27 volts at low current which is more likely to make a heater than a magnet and will exhaust the batteries rather quickly. If you want to compensate for the wimpiness of a 9V, put them in parallel at least. 9V is still more than enough voltage to create a magnet and you'll be able to get 3 times the current out of the batteries.

From your description it sounds like you wrapped the wires correctly, so I'll guess that you simply weren't getting enough current out of the batteries. Take a look at the links i posted, see if your magnet looks like those, and try it again with either a lantern battery like we show on the Science Buddies site or your three batteries in parallel.

I never thought of connecting them in parallel. Thanks a lot!

I will try it , hope it works.