PROBLEM ON RESISTORS IN SERIES
The current flowing in a circuit containing four resistors connected
in series is I = 1.0 A. The potential drops across the first, second
and third resistors are, respectively: V = 5 V, V = 8 V and
V = 7 V.
The equivalent resistance of the circuit is R = 30.
|Find the total voltage supplied by the battery, and also current, voltage
drop, and resistance of each resistor in the circuit.
Figure 1 Example Problem: Resistors in series
How are resistors related when connected in series?
What is true about potential drops of resistors when connected in series?
You will need to use Ohm's Law.
Because the resistors are connected in series, then the same current flows
through each one. Using the Ohm's Law, we can find the resistances of the
first, second and third resistors.
Now, using the equivalent resistance, we can find the resistance in the
fourth resistor. This is a series circuit, so the equivalent resistance
is the sum of the individual resistances.
The current flowing through the fourth resistor is also I=1.0A. Using Ohm's
Law again, we find the voltage across this resistor.
The total voltage supplied by the battery must equal to the total voltage
drop across the circuit (this is known as Kirchhoff's
Voltage Law). So, we must sum up the voltage drops across the resistors.
Figure 2 Example Problem, with given data
|First, let's label the diagram with the information given in the question.
There are several ways of solving this problem (see alternate
solutions), but this tutorial will only go through one of these ways.
of Resistors in Series
to: Resistors in Parallel
DC Circuits Menu
Physics Tutorial Menu