# How to determine the minimum proximity of magnet to an AC line for no electrical impedance?

As the title says, I am wanting to calculate the minimum proximity for a magnet to be near a AC line for no electrical impedance.

My scenario is this: I have a theoretical device like MagSafe (Apple's magnetic DC connector for laptops) however with one main difference, it would be with AC instead of DC. My understanding is that a magnet could cause the Proximity effect and create an electrical impedance.

To avoid the impedance but still use a magnet in close proximity in a "MagSafe" like device, I could simply move the magnet further away from the current. The part that I don't know is how to calculate the minimum distance required. I gather that I would need to determine the magnet's strength but I am unsure what other parts I need for the calculation (does the AC voltage matter for the proximity? can the proximity be affected by shielding the AC line somehow?).

The AC voltage in my case would follow the AS60038 standard (230v, +10% to –6% variation)

If this was a real device (rather than theoretical), I gather that I could simply measure the AC voltage etc and move a magnet around it to find out however I am curious how one could do this theoretically.

• Looks at larger profile photo. If that's you then I'm sure you know who I suspect people have said you look like :-). Commented Jan 10, 2015 at 14:47
• Yep that's me in the photo though to be honest, no one has mentoned to me who I look like (though I really want to know now!). They do mention I look like a 12-16yo. ;) Thanks for your help by the way, have learnt a few new things. Commented Jan 10, 2015 at 22:35
• One may have to squint somewhat to see a resemblance - Harry Potter came to mind :-) - I think that would usually be a compliment. Commented Jan 11, 2015 at 4:18
• Ahhhh ;) Only thing missing is the scar. Commented Jan 11, 2015 at 4:21