Clive W. Humphris

**CIRCUIT THEOREMS: Superposition Theorem 1. **

When a circuit has multiple sources of voltage the current flowing at any one point will be a sum of the currents from each source and each power supply will act like a short circuit on another power supply. In this example the R3 current is made up of electrons from both batteries. Each battery contribution will depend on the source voltage and the associated resistor values.

Applying the Superposition theorem means we consider the each half of the circuit as if it is supplied from one source, i.e. V1 with V2 shorted and then V2 with V1 shorted. The potential difference across R3 will be a sum of these quite separate calculations.

The effect of shorting out the battery is to place the resistor on that side of the circuit in parallel with R3. Remember their combined value will always be lower than the smallest one. The voltages Va and Vb at the potential divider junctions are then calculated and added. This is the resultant voltage across R3.

Circuit currents can be found by applying Ohm's Law.

- Table of Contents
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- Basic Electronics
- Conductor And Insulator
- Resistor Value Test
- Simple Dc Circuits
- Types Of Switching
- Variable Voltages
- Ohm's Law
- DC Voltage
- DC Current
- Series and Parallel Resistors
- AC Measurement
- AC Voltage and Current
- AC Theory
- RCL Series
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- Capacitance
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- Inductance
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- Radio and Communication
- Tuned Circuits
- Attenuators
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- Oscillators
- Circuit Theorems
- Complex Numbers
- DC Power
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- Silicon Controlled Rectifier
- Power Supply
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- Electro-Magnetism
- Electrical Machines
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- Energy Transfer and Cost
- Atomic Structures
- Diode Theory
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- Transistor Theory
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- Active Transistor Circuits
- Field Effect Transistors
- Basic Operational Amplifier
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- Sum and Difference Amplifiers
- Analogue Multi-Meter
- Component Testing