# Diamagnetism experiment with copper/lead

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1. Aug 8, 2017

### JoeSalerno

I'm new to the concept of diamagnetism, but it seems very fascinating, and I'd like to try a simple experiment. Say I wanted to repel a small piece of lead (or copper, both are readily available to me) about 3.5 grams, how strong of a magnet would I need? Could I just use small neodymium magnets or would a more serious electromagnet be needed? Is there a way to calculate the needed magnetic field strength and compare it to the magnetic susceptibility value of lead or copper? Excuse me if I've made any fundamental errors, as I've only really read about it a bit on the internet.

2. Aug 8, 2017

### Staff: Mentor

It is a weak effect, but you can demonstrate it with permanent magnets if you have a setup that reacts to small forces. Here is an example with a rolling soda can.

3. Aug 8, 2017

### JoeSalerno

From what I've read, you can't increase the diamagnetic strength of an object, but increasing the strength of the magnetic field it is present in pushes it away harder. If you theoretically had a super strong permanent or electromagnet, would you be able to repel the small sample of lead?

4. Aug 8, 2017

### Staff: Mentor

Every moving magnet will lead to a force, stronger magnets just lead to stronger forces. There is no threshold.

5. Aug 24, 2017

### f95toli

In case it is not obvious: the force due to diamagnetism in metals such as copper and lead is so small that the effect is tiny even in very large fields. The force is small that it is not something one needs to think about even when dealing with say 14T superconducting magnets.
Note that the famous levitating frog was in the bore of a 16T magnet.

Directly seeing the effect in experiment that can be done at home would most likely be impossible

6. Aug 24, 2017

### Staff: Mentor

Bismuth's diamagnetism is so strong that you can levitate it with strong permanent magnets. You can buy pieces of bismuth and do it at home.

7. Aug 24, 2017

### f95toli

Indeed, but the susceptibility of bismuth is something like 20 higher than that of of copper and lead (which means the effect can be seen at ~1T which is the field you get from a strong RE magnet).

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