Question

Remember that the current coming into a junction equals the current coming out of the junction.

Also bear in mind that voltage is basically a height difference between two points.

1) If you measure the potential across two batteries and find that V1 = 1.3V and V2 = 1.4V,

then you measure the potential between the negative ends of battery 1 and positive end of

battery 2 and get V12-+ = -0.1 and the potential between the positive ends of battery 1

and negative ends of battery 2 gives V12+- = 0.1, what is the potential between the

negative end of battery 1 and the positive end of battery 2? What about the potential

difference between the negative end of battery 2 and the positive end of battery 1?

2) Draw a circuit diagram of all the voltage measurements from question 1. (These should

still all be closed circuits)

3) So, since the two answers in question 1 are different, what is a practical application of

this knowledge (that battery order changes effective voltage)? For the one I’m thinking

of, consider that you have a remote control with two AA batteries and it dies while you

have no replacement batteries on hand. If you have other practical applications, I’d also

love to read them.

4) Suppose you have two light bulbs with a resistance of 100 ohms and a 1.5 V battery set

up like the series and parallel circuits in the first circuit lab. Using Ohm’s law and the law

that current into a junction equals current out of the junction, determine the current in the

light bulbs and battery for both circuits. Do these numbers agree with your observations

in that lab? (They may not) If not, why not? (You might have to make a reasonable

educated guess for the parallel circuit)

Answer 1