Voltage Across C3 Calculator

Calculator Form

Supply voltage

Voltage type

Circuit topology

C1 value

C2 value

C3 value

Capacitance unit

Frequency for reactance

Initial C3 voltage

Capacitor tolerance percent

C3 voltage rating

Output options

Example Data Table

Supply	C1	C2	C3	Topology	Approx C3 Voltage
12 V	10 uF	22 uF	47 uF	Series	1.73 V
24 V	10 uF	10 uF	10 uF	Series	8 V
9 V	4.7 uF	10 uF	22 uF	C1 \|\| C2, series C3	3.61 V
5 V	1 uF	2.2 uF	4.7 uF	C3 parallel source	5 V

Formula Used

Capacitance conversion: C in farads equals entered value times unit multiplier.

Three capacitors in series:

Ceq = 1 / (1/C1 + 1/C2 + 1/C3)

Q = Ceq × Vs

VC3 = Q / C3

C3 directly across the supply:

VC3 = Vs

C1 and C2 parallel, then series with C3:

C12 = C1 + C2

Ceq = (C12 × C3) / (C12 + C3)

VC3 = (Ceq × Vs) / C3

Energy stored in C3:

E = 1/2 × C3 × VC3²

Capacitive reactance:

XC3 = 1 / (2πfC3)

How to Use This Calculator

Enter the supply voltage first. Select whether the value is DC, AC RMS, or AC peak. Then choose the circuit topology that best matches your diagram.

Add C1, C2, and C3 values. Pick the shared unit from the unit list. Add frequency when you want reactance for AC review.

Use initial C3 voltage when a capacitor may already be charged. Add tolerance and voltage rating for a simple safety review. Press Calculate. The result appears above the form.

Use the CSV button for spreadsheet work. Use the PDF button for a quick printable result sheet.

Understanding Voltage Across C3

Why C3 Voltage Matters

The voltage across C3 is important in many capacitor networks. It helps check divider behavior, stored energy, insulation stress, and safe component selection. A capacitor can fail when its voltage rating is exceeded. So the calculated value should be compared with the real rating.

Series Capacitor Behavior

In a pure series capacitor chain, every capacitor carries the same charge. The voltage does not split like equal resistors unless all capacitance values are equal. The smallest capacitor usually receives the largest voltage share. This happens because voltage equals charge divided by capacitance.

Parallel and Mixed Networks

When C3 is parallel with the source, its voltage equals the source voltage. Mixed networks need an equivalent capacitance step. Parallel capacitors add directly. Series groups use reciprocal addition. After finding the equivalent value, charge and voltage division can be found.

AC Review

For AC circuits, capacitance also creates reactance. Reactance depends on frequency and capacitance. Higher frequency lowers capacitive reactance. Larger capacitance also lowers reactance. This calculator reports C3 reactance so designers can compare voltage and impedance effects together.

Safety and Tolerance

Real capacitors are not exact. Their values change with tolerance, temperature, age, and applied voltage. Ceramic capacitors can shift strongly under bias. Electrolytic capacitors can have wide tolerance. The tolerance range in this tool gives a practical estimate, not a final certified design limit.

Practical Use

Use this calculator during circuit study, repair checks, hobby electronics, and early design work. Match the topology carefully before trusting the answer. When working with high voltage, discharge capacitors before touching the circuit. Use a proper meter and safe procedures. For final products, confirm results with simulation, measurement, and component datasheets.

FAQs

What does voltage across C3 mean?

It means the electric potential difference between the two terminals of capacitor C3. This value shows how much electrical stress C3 has in the chosen network.

Does C3 always get the full supply voltage?

No. C3 gets full supply voltage only when it is directly parallel with the source. In series or mixed networks, voltage depends on capacitance values and circuit structure.

Why does a smaller series capacitor get more voltage?

Series capacitors carry the same charge. Since voltage equals charge divided by capacitance, a smaller capacitance produces a larger voltage for the same charge.

Can I use this for AC circuits?

Yes, you can enter an AC RMS or peak voltage. The calculator also estimates C3 reactance when frequency is entered.

What unit should I choose for capacitance?

Choose the unit printed on your capacitor or circuit diagram. Common units are microfarads, nanofarads, and picofarads.

What is stored energy in C3?

Stored energy is the electrical energy held by C3 at the calculated voltage. It is found using one half times capacitance times voltage squared.

Why include capacitor tolerance?

Tolerance helps estimate how component variation may change the voltage. Real capacitors rarely match their marked value exactly.

Is this calculator enough for high voltage design?

No. Use it for estimates and learning. High voltage designs need datasheet checks, safety margins, simulation, testing, and proper discharge procedures.