When you run a magnet across a plate of aluminum you can easily feel the eddy currents creating an opposing magnetic field which resists your movement. I tried this with a plate of steel and noticed that there was hardly any resistance. Was wondering why this?
Likely because the steel has about an order of magnitude higher resistance than aluminum and thus the eddy currents are much smaller. The opposing magnetic field is proportional to this current.
for steel it's 1.611 to 7.496 × 10-7 Ωm
for aluminum its 2.82 × 10-8 Ω·m
so it depends on which kind of steel that you use. The attrative force will be always stronger than eddy currents, so we may no 'feel' anything on cast steel.
I think this is the reason.
I am getting major conflicting information. I am finding charts saying that the resistance of Aluminum vs Steel is not that different, but also charts which show that the conductivity of aluminum is way better?? I thought resistivity and conductivity were inversely proportional...?
I am getting major conflicting information. I am finding charts saying that the resistance of Aluminum vs Steel is not that different, but also charts which show that the conductivity of aluminum is way better?? I thought resistivity and conductivity were inversely proportional...?
Can you screen print or snip one of those charts that says the electrical resistance is the same? As crutschow noted, there is an order of magnitude (i.e., 10 fold) difference. Aluminum is the better electrical conductor.
Can you screen print or snip one of those charts that says the electrical resistance is the same? As crutschow noted, there is an order of magnitude (i.e., 10 fold) difference. Aluminum is the better electrical conductor.
For the resistance I was going by what magvitron said in the post above. His numbers seem to suggest that aluminum has similar resistive properties to steel. Unless I'm reading it wrong.
1e-7 is a larger number than 1e-8 so re-read that.
Also, how are you preventing the magnet from touching the steel during your 'steel' test? Remember the distance to the object has to be the same for both materials or the test is not comparable.