You are unlikely to encounter a circuit with just one power supply and two resistors in your exam. However, you can simplify any series resistors to just one combined resistor within a more complicated circuit.
Remember that you can annotate a circuit diagram (or sketch simplified versions) as you go through a problem.
The current in a series section of a circuit is constant. Therefore, the current through each series resistor is the same. The potential differences across the resistors sum: \(V_T=V_1+V_2+...\).
This means that the resistance of the combination is the sum of the individual resistors:
\(R_T=R_1+R_2+...\)
NB: Many students believe that current should get 'used up' around the circuit. How could you amend this statement?
Use quizzes to practise application of theory.
START QUIZ!
Calculate the resistance between A and B
The top resistor isn't connected the other 2 are in series.
What is the total resistance when the switch is closed.
All three are in series
Calculate the current that will flow when the switch is closed.
I = V/R = 10/20
What is the current I?
Curent is the same all round the circuit.
What is the Pd V?
V = IR = 1 x 5
How much of Series resistors have you understood?
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