Physical Science / Unit 10: Electricity and Magnetism
10.4 Series and Parallel Circuits
Notes
- Series circuit: one path for current. The current is the same everywhere. If one device fails, all stop. Resistances add: $R_{total} = R_1 + R_2 + \dots$
- Parallel circuit: multiple paths. Each branch has the same voltage. If one branch is open, the others keep working. Household wiring is parallel.
- Example (series): 10 $\Omega$ and 20 $\Omega$ resistors with a 6 V battery. $R = 30\ \Omega$, so $\displaystyle I = \frac{6}{30} = 0.2$ A.
- Adding more devices in parallel increases total current drawn from the source.
Practice
In a series circuit, if one bulb burns out, the other bulbs:
Series circuits have one path, so a break stops all current.
Three resistors of 2 $\Omega$, 3 $\Omega$ and 5 $\Omega$ are connected in series. What is the total resistance?
Series resistances add: $2 + 3 + 5 = 10$.
Why are home outlets wired in parallel?
Parallel branches have the same voltage and can operate separately.
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