# Need help veryfing E&M Multiple Choice

1. Oct 4, 2004

### vsage

Need help verifying E&M Multiple Choice

(True/false) (Referring to a diagram that is an ideal battery with wires connecting the positive and negative ends to a resistor in the form of a lightbulb of 30 ohm resistance creating a circuit). I'm also fairly sure the wires resistances are 0.1 ohm
-To a good approximation the current in the circuit can be calculating assuming wires have zero resistance. True?
-To a good approximation the voltage drop across the wires will be the same as that across the other circuit elements. False?
-To a good approximation the voltage across any other element in the circuit will be the same as if the wires actually did have zero resistance. True?

These next ones refer to a circuit like the above except there's a wire (Wire B) that connects from just outside the positive wire (wire A) running into the lightbulb (L2) to just outside the negative wire (Wire C) running into the lightbulb. There's also now a lightbulb(L1) spliced into the positive wire (wire A). Also, assume the wires have a low resistance compared to the lightbulbs.

-To a good approximation, wires A, B and C can all be taken to have zero resistance. True?
-To a good approximation, only wires A and C will carry current and wire B carries almost no current. False?
-To a good approximation, L1 will have a full power supply across it. True?
-To a good approximation, L2 will have the full power supply voltage across it. True?
-To a good approximation, L1 will have 0 current. False?
-To a good approximation, L2 will have 0 current. False?

I'm so confused. These prelab questions made me read ahead in the book but no examples in the book take into account wires with resistance! The book just sort of skips over circuits and goes right into Magnetism.

Edit I only have mspaint to make a drawing in so I don't know if it would help any.

Last edited by a moderator: Oct 4, 2004