Clive W. Humphris

**CAPACITANCE: Capacitor Charging. **

Connecting a capacitor in series with a resistor across a steady DC supply causes the capacitor to eventually become charged to a voltage equal to the battery. The time it takes is determined by the resistor and capacitor values.

Normally the capacitor is considered to be charged when the voltage reaches 63% of the supply voltage. This takes a period of time equal to C × R in seconds.

The reason for the exponential waveform shape is that when the capacitor is uncharged it is effectively a short circuit and a relatively high current flows, determined mostly by the value of R. As the capacitor charges a voltage is developed across it which opposes or subtracts from the applied voltage (V).

As V - VC decreases and VC approaches V, the charging current tends towards zero. It takes a period of approximately five time constants for C to become fully charged (or discharged).

- 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
- RCL Parallel
- Capacitance
- Capacitors
- Inductance
- Inductors
- Impedance
- Tuned Circuits
- Attenuators
- Passive Filters
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- Oscillators
- Circuit Theorems
- Complex Numbers
- DC Power
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- Silicon Controlled Rectifier
- Power Supply
- Voltage Regulation
- Magnetism
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- Energy Transfer and Cost
- Atomic Structures
- Diode Theory
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- Transistor Theory
- Bipolar Transistors
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- Active Transistor Circuits
- Field Effect Transistors
- Basic Operational Amplifier
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