Physics 2240
2/22/2016
Experiment #4B
Series Parallel Circuits
Devin Davis
Introduction:

Simple circuits are connected by their components in a series and/or parallel
arrangements. The components are usually called resistors and are hooked up to a battery source
to create a current. A simple/complex circuit can be reduced to an equivalent resistance, which
will equal the same current as the resistors. In this experiment, 4 different circuits will be
examined and discussed. The behavior of parallel and series circuits are also studied throughout
the experiment. The equivalent resistance is obtained by calculating Current (I) and measured
Velocity (V). Percent difference between the theoretical and measured equivalent resistance will
be measured for all 4 of the circuits.
Theory:
A circuit contains resistors that establish a current throughout the circuit system.
Resistors are assumed in this experiment to obey Ohm’s Law and have a resistance of R.
Resistors (two or more) can be connected in series or parallel. They also can be connected in a
complex circuit containing a series/parallel circuit. An equivalent resistance is a single resistor
that can replace a complex circuit, but still produce the same amount of current (if the voltage
doesn’t increase/decrease). In a series circuit the resistances are additive to produce the
equivalent resistance:
R
(
equivalent
)
=
R
1
+
R
2
Equation 1
For a parallel circuit, the resistances add as reciprocals:
1
R
(
equivalent
)
=
1
R
1
+
1
R
2
Equation 2
Equation 1 & 2 will be used for the first 2 circuits respectively, while the last 2 circuits are more
complex. They require noticing that certain resistors are in parallel or series. Circuit #3 consists

of 2 resistors in parallel, who then can be calculated into an equivalent resistance using Equation
2. That equivalent resistance can then be added to the last resistor using Equation 1 to find the