Download ECE1250 Practice Quiz (node,series,parallel)

ECE1250 Practice Quiz.
Label all nodes. Are they ordinary or extraordinary? Which combinations of resistors are in series and
parallel? Which resistors can be eliminated because they are in parallel with a short circuit?
Answers:
The red nodes are ordinary. All others are extraordinary.
Notation: The dash – means they are in series. || means they are in parallel. The voltage source is in
parallel with the resistive combinations given below.
Circuit 1: R2-R5 , R3-R4, R1 || (R2-R5) || (R3-R4)
We say: “R1 is in parallel with the series combinations of R2 and R5, and R3 and R4.”
Circuit 2: R14||R15, R12||R13, (R14||R15) - (R12||R13)
R11||{ (R14||R15) - (R12||R13) }
“R11 is in parallel with the series combination of R14andR15 in parallel and R12andR13 in
parallel.” (Ok, at about this point in the conference call, you better send a circuit diagram….the
spoken description gets confusing quickly.)
Circuit 3: R7-R10, R8-R9, R6|| (R7-R10) || (R8-R9) || short circuit
Anything in parallel with a short is ‘shorted out’, no current will pass through it, and it can be
removed from the circuit. You can remove all of the resistors. The voltage source is effectively
shorted out (hopefully the circuit has a fuse or circuit breaker that will open to prevent the
current from running away (going to infinity) and burning up the circuit.