Electric can opener puzzle

How does my $10 counter-top electric can opener know to stop after the can rotates 360 degrees and the lid is severed all around and sticking to the spring-loaded magnetic arm?
I don't see any kind of sensor or probe and the rotation can't be time-dependent because it works with different diameter cans.
So how?
--
If people, who cross our border illegally are not Illegal— then what are
they?
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The magnet is holding down the "run switch" until it (the lid) lifts from the can.
--
RonNNN

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.