DC Theory Tutorials

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.

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 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 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.

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

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 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.

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.

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.

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.

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.

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.

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.

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