View Single Post
Old 01-10-2019, 08:56 AM   #4480 (permalink)
RedDevil
In the fasting lane
 
RedDevil's Avatar
 
Join Date: Dec 2012
Location: Nieuwegein, the Netherlands
Posts: 3,988

Red Devil - '11 Honda Insight Elegance
Team Honda
90 day: 50.29 mpg (US)
Thanks: 1,705
Thanked 2,229 Times in 1,444 Posts
You do not need any energy to maintain the magnetic field in an electromagnet!
The only power an electromagnet consumes is what's needed to overcome the resistance of the conductor.

If you do not have resistance, like when the coil is cooled down until it is superconductive, you could short the ends and the magnetic field would be like a permanent magnet.

If you want to change the strength of the magnetic field then you need to change the strength of the current, which requires of provides power.

If there was a way to change the strength of a magnetic field of a permanent magnet, that would of course require power, just like it does with an electromagnet.

Bear in mind that introducing a magnetic field influences all charged moving particles (like all electrons in an atom).
If you drop a strong magnet down on a conductive plate that will cause a current circling round in the material, forming an electromagnet with opposing flux, slowing down the approach of the magnet.
If that plate is superconductive then the magnet will come to a standstill, hovering above the plate, kept in balance by the opposing magnetic field it created in the plate by approaching it.

https://www.scientificamerican.com/article/how-do-they-do-that-a-closer-look-at-quantum-magnetic-levitation/


The plate material is de facto an electromagnet, 'powered' by the intrusion of the magnetic field of the small magnet above. It does not need energy to maintain its field; rather, the longer energy (heat) is kept away, the longer it persists!
__________________
2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.17 Gmeter or 0.1 Mmile.



Investors woes:
"In hindsight, I should have placed a bet on the horse that won the race"
"In hindsight, I should have bet more on that horse"

Last edited by RedDevil; 01-10-2019 at 09:16 AM..
 
The Following 4 Users Say Thank You to RedDevil For This Useful Post:
aerohead (01-12-2019), All Darc (01-10-2019), freebeard (01-10-2019), niky (01-10-2019)