Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

kirchoff's rules - New Thread



Hi All,

Today one of my students asked me about Problem 23 in
Chapter 28 of the 5th edition of Serway: Physics for
Scientists and Engineers.

The class had done many similar problems for homework and
help session exercises. They are fairly adept at
rearranging and redrawing circuits before analyzing them.
The did the same with this problem and redrew the circuit
eliminating the wire between points a and e. Disaster!!!
Even though the Voltage difference is zero between these
two points, tying them together gives no way to find the
current through the wire. A simple Kirchoff problem
involving two loops and a junction became three loops and
two junctions to get the five currents involved (if you
don't tie the two points together.)

Have any of you encountered this problem before. Do you
have a simple intuitive argument that I can use with my
students to convince them that it is unwise to redraw this
particular circuit. The Serway answer book gives a solution
where the points are tied together to do part of the
calculation and then untied to complete it. The solution is
clever, but beyond the average student.

Bob at PC