Iron / steel has much higher resistance than copper (so-called resistance wire for domestic heating elements is usually steel).
Resistance heating due to eddy currents is the only source of heat in induction; domain flips are fueled by ambient phonon exchanges (the principle exploit in MCE allowing adiabatic / isothermal cycling), but heat in = heat out for any closed hysteresis loop. Measure the steel's resistance with a meter, then find a thin piece of copper - resistance is a function of cross-sectional area, so thin piece of copper can have equal resistance to a thicker piece of steel.. in which case you should get similar heating. On Sun, Feb 28, 2016 at 6:34 PM, H Ucar <jjam...@gmail.com> wrote: > I observed dramatic heating of iron/steel rods of 2-4 mm diameter at 5 to > 10 mm distance to spinning Nd magnet of medium size above 8000 RPM (poles > nearly ortogonal to spin axis) where strong attraction is present. Motor > consumes extra 2-3 watts on this load. Heat can rise to 80 degrees C in > less than a minute, I guess, enough to melt hot glue. One atypical thing is > the hottest part is not the closest point to the spinning magnet, so far I > observed. Similar rods made of non ferromagnetic metals are not heated and > practically don't load the motor. Only large copper and Al blocks slow down > the motor but heating is not apparent. > > Any alternative explanation? > > >
