Capacitors in Parallel
Parallel capacitances add.
Formula
Variables
How it works
When capacitors are connected side by side across the same two nodes, each one experiences the same voltage. Because charge stored on each capacitor is proportional to that voltage, the total charge is just the sum of the individual charges, which makes the equivalent capacitance equal to the sum of the capacitances. This is why adding capacitors in parallel increases the total ability of the circuit to store charge.
When to use it
Use this formula whenever you need the single equivalent capacitance of multiple capacitors connected across the same two points in a circuit. It is especially useful in circuit analysis, battery-backed circuits, and when combining capacitor values to reach a desired total capacitance.
Worked example, step by step
Three capacitors are connected in parallel: C1 = 4.7 µF, C2 = 10 µF, and C3 = 22 µF Step 1: Write the parallel-capacitance formula: Ceq = C1 + C2 + C3 Step 2: Substitute the values: Ceq = 4.7 µF + 10 µF + 22 µF Step 3: Add them: Ceq = 36.7 µF Final answer: The equivalent capacitance is 36.7 µF.
Common mistakes to avoid
- Adding capacitors in parallel by using the reciprocal formula, which is only for series connections
- Forgetting that all capacitors in parallel share the same voltage
- Mixing units without converting them consistently before adding
Did You Know?
Capacitors in parallel simply add, the opposite of resistors, because you are effectively enlarging the plates.
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