In a message dated 2006/11/13, gmvoeth@........... writes:

> WHY ??
> > In a message dated 2006/11/13, gmvoeth@........... writes:
> >> Ever thought of possibly using a coin ?
> >> 
> > Hi Geoff,
> >       Copper coins are not pure copper. They are a hard alloy which is 
> > resistant to  wear - NOT what we want!

Hi Geoff,
 
       Because hard alloys have a much greater electrical resistivity than 
pure Cu and hence you get a greatly diminished damping force. Try sliding a 
magnet down an inclined plane of Cu or Al and then try it with brass or Duralumin.

       Regards,

       Chris Chapman
In a me=
ssage dated 2006/11/13, gmvoeth@........... writes:



WHY ??

> In a message dated 2006/11/13, gmvoeth@........... writes:

>> Ever thought of possibly using a coin ?

>> 

> Hi Geoff,

>       Copper coins are not pure copper. T=
hey are a hard alloy which is 

> resistant to  wear - NOT what we want!




Hi Geoff,

 

       Because hard alloys have a much greater=
 electrical resistivity than pure Cu and hence you get a greatly diminished=20=
damping force. Try sliding a magnet down an inclined plane of Cu or Al and t=
hen try it with brass or Duralumin.



       Regards,



       Chris Chapman