I'm currently working on a school project.  We're suppost to design a
simple system (simple to use rather) to detect a burnt-out bulb in a
Christmas light strand.

First idea which came to mind was sensing the EM Field produced by the
strand when a bulb is missing.  Could anyone better suited in EM fields
offer any advice?  A hall-effect sensor may be useful in this app., but
again, I've never used one (just know how they work).

Best Regards,

Vincent Deno