PHYS 2240-Section 516
Lab 4B Report
In this experiment, we reduce series parallel circuits to an equivalent resistance. We
then confirm that resistance experimentally by measuring the total current and the total
voltage. We then use Ohm’s Law to find the resistance by dividing the measured voltage by
the measured current. The importance of this experiment is to determine the relationships
between series parallel circuits and their equivalent resistors as well as to use Ohm’s Law
to find the relationship between voltage, current, and total resistance.
A resistor is a device that resists the passage of an electric current, and in general, it
obeys Ohm’s Law. Resistors can be connected in one of three ways: in series (see Circuit
Diagram 1), in parallel (see Circuit Diagram 2) or in a series parallel combination (see
Circuit Diagrams 3 and 4).
An equivalent resistor is a single resistor that can replace a
complicated series parallel circuit to produce the same resistance. It thus produces the
same current as the original series parallel circuit as long as we apply the same total voltage
to both systems.
For a series circuit, we can add the individual resistances to calculate the equivalent
resistance, as shown in Equation 1. For a parallel circuit, we instead add the reciprocals of
the individual resistances to calculate the reciprocal of the equivalent resistance (Equation
2), which we can then invert to find the true equivalent resistance. We can combine and
manipulate these two equations to find the equivalent resistance for increasingly
complicated series parallel circuits.
Equivalent Resistance of aSeriesCircuit
In this equation, R
represents the equivalent resistance, and R
represent the individual resistances of the components
of the system
Equivalent Resistanceof a