# DC Theory Tutorials

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## Direct Current (DC) Theory Tutorials

## Current Divider Rule in parallel resistors

By using the current divider rule, we can find the current in each resistor connected in parallel. The electric current passing through a circuit of two resistors in parallel is divided in two.

## What is the Internal Resistance of a Voltage Source?

Voltage sources, whether batteries, generators, etc., are not ideal (perfect). A real voltage source is composed of an ideal voltage source in series with a resistance called internal resistance.

## Ohm’s Law and the Electric Power – Formulas

Ohm’s Law relates in one equation the voltage, the current and resistance. Resistance = Resistor’s value. A more complete expression of Ohm’s Law is achieved using the electric power formula

## Ohm’s Law Tutorial – Ohm’s Law Triangle

Ohm’s law states that the voltage across a resistor is directly proportional to the current flowing through the resistance and directly proportional to the resistance of the circuit.

## Mesh Current Method in a Resistor Network

The Mesh current method is very useful to know all the current in a network of only resistors. This method, a little more extended, is also applied to circuits where there are resistances and reactances.

## Millman’s Theorem – Millman’s equivalent circuit

Millman’s theorem is used to directly obtain the voltage between the ends of a parallel branch circuit. Equivalent Millman circuit Formulas, example.

## Voltage – Electrical Potential Difference

Potential difference or Voltage is a kind of force that push charges through a conductor. The larger the voltage, the larger the force

## Benjamin Franklin’s Fluid Theory

Benjamin Franklin imagined the electricity as a invisible fluid. Franklin assured that if any body had more fluid than usual, it could have a positive charge, but if it had less fluid than normal it had negative charge.

## Voltage Divider Rule

The Voltage divider is a circuit that allows us to obtain an output voltage less or equal to the input voltage. The output voltage is normally obtained across ground and the resistor connected to it, but it could be across any of the other resistors.

## What is Direct Current? – What is DC?

Direct Current (DC), is the result of the flow of electrons (negative charge) in a conductor (most of the time, wires of copper) that goes only in one direction.

## Superposition Theorem – Example

The Superposition Theorem

The Superposition theorem states that the effect of two or more voltage sources in a resistor is equal to the sum of the individual effects of each source taken separately, replacing all the remaining voltage sources with short circuits.

## First Right Hand Rule

The First Right-hand Rule or (Magnetic Force induced on a Current-Carrying Wire) says that if a current-carrying wire is in the presence of a magnetic field, a force is exerted on the wire.

## DC Motor – Parts of a DC Motor. Basic Operation Principle.

DC Motor

A DC motor is composed of a stator and a rotor. In many small motors, the stator is composed of magnets. Larger motors have windings.

## What’s Static Electricity? – Examples

Static electricity is static, since it is a current that is going nowhere. Both, DC and AC current flow in some direction, but static electricity does not.

## Energy and Electric Power. Performance

Power is the speed at which work is done. Electric power is the multiplication of the current (amps) by the voltage (volts). P = I x V.

## Step Response of RL Circuits

When a constant voltage is suddenly applied to an RL circuit, an increasing a current goes through the conductor and creates a magnetic field that expands with the increasing current

## Norton’s Theorem

Norton’s Theorem The Norton’s Theorem is similar to the Thevenin’s Theorem. It can be seen that, the equivalent circuit is: A Voltage source (Thevenin voltage: Vth) in series with a resistor (Thevenin resistance: RTH) Thevenin…

## Thevenin’s theorem

The Thevenin’s theorem is used to convert a two terminal circuit, into a very simple circuit containing one voltage source in series with a single resistor

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