# Lab on Resistors in Series and Parallel

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```					Lab on Resistors in Series and Parallel
Objective: a) To learn the difference between electrical connections in series
and parallel circuits
b) To practice building circuits in series and parallel on circuit boards
c) To use experimental results to formulate laws for series and
parallel resistors

Procedure:

a) Take 4 identical resistors and the volt/ohmmeter, fill in the following table by
first measuring the resistance of the single resistors and then combining them in
series on the circuit board, finding the total resistance for each type circuit

R1     R2       R3      R4     Rtotal     Sketch the circuit here
()    ()      ()     ()    ()
Using 2
resistors only                   X       X
Using 3
resistors only                           X
Using 4
resistors

Questions:

1) How many paths are there for current to flow in a series circuit?

2) What happens to the total resistance as you add resistors in series?

3) What is a mathematical law of resistors in series?

4) Give an example of this law for three resistors in series:
b) Take 4 identical resistors and the volt/ohmmeter, fill in the following table by
first measuring the resistance of the single resistors and then combining them in
parallel on the circuit board, finding the total resistance for each type circuit

R1      R2      R3      R4      Rtotal    Sketch the circuit here
()     ()     ()     ()     ()
Using 2
resistors only                   X       X

Using 3
resistors only                           X

Using 4
resistors

Questions:

5) How many paths are there for current to flow in a parallel circuit?

6) What happens to the total resistance as you add resistors in parallel?

7) What is a mathematical law of resistors in parallel?

8) Give an example of this law for three resistors in parallel:

9) Prove this statement: the total resistance of parallel resistors is always less than that
of the smallest resistor. Your can show this proof by showing your calculations for
the following circuits:

a) a parallel circuit with three resistors: 3 ohm, 8 ohms, and 24 ohms (do a sketch)
b) a parallel circuit with three 100 ohm resistors and one 5 ohm resistor (do a sketch)