How do you connect circuits?

Question

Tomorrow I have a lab exam. It can be about pH scales, acids, bases, and salts, or magnets. I'm fine with all the other topics, but I am not sure about the circuits exam. How would you connect a voltmeter and ammeter to both a series and parallel circuit? (The way we did this in class was with alligator clips and a power pack. Also, our resistors were these little blocks with wires sticking out.)

Answer 1

It's easy.  There are some simple rules to remember about using a voltmeter and an amp meter in simple series and parallel circuits.

In a series circuit where you have, say, resistor 1 (R1) connected to resistor 2 (R2).  I'm assuming that the series resistors are connected to battery or power source.

In a series circuit, the current flow is the "same" in all parts of the circuit.  So, it doesn matter where in the circuit you connect up the amp meter. However, you do have to connect the amp meter in "series" with the circiut and, you have to observe the polarity of the meter.  Break the series circuit at any point and connect the + lead from the amp meter to the circuit coming from the + side of the battery.  Do the same for the -- side of the amp meter.  If you have it connect right, it will read either (left to right on an analog meter), or it will read plus digits on a digital meter.

Remember that in a series circuit, the voltage drops across each series resistor must add up to equal the supply voltage or battery voltage.  To measure voltage drop across a resistor, using a "volt meter," make sure your meter is set to read a voltage "higher" than your supply or battery voltage. Connect the red positive lead across the resistor to be measured, and the black negative meter lead across the other side of the resistor, observing polarity as before.  Reduce your volt meter setting until you get a good mid-range reading. Repeat this for each resistor in the series circuit. Again, all the voltage drops must add up to equal the supply voltage.

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Parallel circuits:

Voltage across any parallel circuit is the "same" for all branches in the parallel network.

Current in each branch of the parallel resistor network will vary with the resistant value in that particular branch.  All branch currents must add up to equal total circuit current.

To measure voltage across a parallel resistor network, set you meter to a range a little greater than your supply voltage. Place the red positive lead across the network closest to the positive supply voltage terminal. Place the black negative lead of the volt meter across the opposite side of the network.  The voltage read on your meter is the same across all resistors in the parallel network.

To measure current using your amp meter, you will do it in the same way that you did for the series circuit, but you will install your amp meter in series with "each" resistor branch in the network.  The current meter reading for each branch current, when added together, must equal the total current flowing into and out of the parallel network.  Don't forget to observe polarity requirments.

I hope that is descriptive enough to help some.

Answer 2

alligator clips  on wires works fine.