Basics
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Current
Current describes the flow of electrons.
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Power
Power is the product of voltage and current. (P = V x I)
Power is the rate of energy transfer. (W = J / s)
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Voltage
Voltage is the potential to do work and describes the energy transferred when charge flows. (V = J / C)
Voltage is always between two points and has polarity. Voltage can be positive or negative.
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Energy
Energy describes the amount of work.
Energy is measured in Joules (J) or kilo-watt hours (kWh).
Node Voltage and Ground
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Node Voltage
Node voltage is the voltage at the node of a circuit.
If voltage is defined at a single node, in a circuit, it is referred to as node voltage.
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Ground
Ground is the ground node of a circuit. It serves as a critical reference point within electrical circuits, defined as a point that carries a voltage of 0 volts.
Grounding fulfills several vital roles in electronic circuits:
- Reference Point: Ground provides a stable reference potential against which all other voltages in the circuit can be measured.
- Current Return Path: It acts as a common return path for electric current, maintaining a closed circuit necessary for operation.
- Safety: Grounding protects users from electrical shocks by providing a low-resistance path for fault currents.
- Noise Reduction: Ground can shield circuits from electromagnetic interference, minimizing unwanted noise.
There are several types of ground in electronic systems:
- Earth Ground: A physical connection to the Earth that enhances safety by dissipating excess charge.
- Chassis Ground: The metal enclosure of devices that provides both structural support and electrical grounding.
- Signal Ground: A return path specifically for signals within a circuit, crucial for maintaining signal integrity.
- Virtual Ground: Established at a node in certain circuits to maintain a steady reference potential without direct connection to physical ground.
Understanding the concept of ground is essential for designing and analyzing circuits, ensuring safety and reliability in electrical systems.
Ohm's Law & Resistance
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Resistors
A resistor is a device that behaves according to Ohm's Law (R = V / I).
Ohm's Law states that the voltage across a resistor is proportional to the current through it.
Resistors are used to dissipate power.
Resistors can be used to limit the current through a circuit.