Bar magnet wrapped in electromagnetic coil

[coinmaster]

If I wrap a coil around a bar magnet and shoot current through the coil so that the magnetic field of the electromagnet is at the same polarity of the bar magnet will I have amplified the magnetic field of the bar magnet maintaining the same magnetic shape but bigger/stronger?

 

[marcusl]

No. A permanent magnet has a saturated magnetization (it is called "remanent magnetization" on the material's hysteresis curve). Applying additional field will simply add the field of the coil to the field of the magnet.

 

[coinmaster]

Does that mean the field will be stronger but not bigger?

 

[marcusl]

"Stronger" vs. "bigger" doesn't make sense. The field is stronger--it's the sum of the permanent magnetization and the applied solenoidal field. There is no "amplification," used in the sense that a ferromagnetic material produces a strong B field in the presence of a weak H field.

 

[coinmaster]

Could I practically double the strength of a 4''x 0.5'' 35lb strength neo bar magnet using this method without overheating? Current supply isn't a problem for me, assume I have unlimited power for now, but I need to keep the added dimensions to a minimum so I don't know if i can pack that much magnetic strength into that small of an area or not.
If I increase the windings the magnetic field and wire resistance goes up and so does the heat generation limiting the current, if I decrease the windings the current goes up and the magnetic field is proportionally smaller requiring gobs of current. In either scenario I'm not sure whether I can achieve a "doubling" of magnetic strength without cooling methods. What do you think?

 

[marcusl]

Physics Forums isn't a "we'll perform your design engineering for you for free" service. Look at the hysteresis curve and the formula for field from a solenoid. Figure out number of turns, current and heat dissipation and see if you can answer your question.