Understanding Electric Circuits: Components and Principles

Understanding Electric Circuits

An electric circuit is a path through which electrons flow. It typically consists of a generator, a wire conductor, a switch, and a receiver.

Electric Current

Electric current refers to the flow of electrons around a circuit.

Electrical Conductivity

Electrical conductivity depends on the atomic structure of each material:

• Conductors: Allow electric currents to pass through them. All metals are good conductors.
• Insulators: Do not allow electric currents to pass through them (e.g., wood, glass, plastic, air).
• Semiconductors: Have properties between conductors and insulators (e.g., silicon, germanium).

Electrical Resistance

Electrical resistance of a material is a measure of the degree to which the material opposes an electric current flowing through it. Metals have low electrical resistance, while insulators have high levels.

Electric Components

• Generators: Provide energy for electrons to circulate (e.g., batteries).
• Receivers:
  • Light bulb (Light)
  • Motor (Movement)
  • Resistor (Heat)
  • Bell (Sound)

Control Elements

Control elements direct and interrupt electric current:

• Switch: Allows current to flow permanently or to be interrupted.
• Push button: Allows current to flow only when pressure is maintained.
• Circuit switch: Directs current flowing through a branch of a circuit, preventing the current from entering another branch.

Protection Elements

Protection elements protect circuits and people against potential problems:

• Fuses melt in order to interrupt the current when it is too high.
• Breaker switches are automatic fuses.
• Earth-leakage circuit breakers protect against current leakage.

Voltage (Tension)

Voltage, or tension, is the energy that a battery or generator can provide for each electron. It is measured in volts (V). A voltmeter is used to measure voltage and must be connected in parallel to the component whose voltage is being measured.

Electric Current (Intensity)

Electric current is the charge (number of electrons) that flows through a conductor per second:

I (intensity) = Q (charge) / t (time)

It's measured in amperes or amps (A). Electric charge is measured in coulombs (C, 1 C = 6.25 x 10¹⁸ electrons). 1 A = 1 C/s, 1 mA = 10^-3 A, 1 μA = 10^-6 A. It's measured by an ammeter that has to be connected in series with the component whose intensity we want to find out.

Ohm's Law

The resistance of a component is the quotient of potential difference across it over the current flowing through it. This equation is called Ohm's Law:

R (resistance) = V (tension) / I (intensity)

Other variables:

• V = I * R
• I = V / R

Series Circuits

Two or more elements in series when the exit of one is the entrance of the next. The current that flows through all the elements is identical, and the total voltage is the sum of the voltage across each element. The total resistance is R = R1 + R2 +... Several generators in series voltage is V = V1 + V2 +...

Parallel Circuits

The elements have the same entrance and exit. The potential difference of each element is the same, but the current is different. Resistance is calculated as 1/R = 1/R1 + 1/R2 +... Several generators in parallel will supply the same voltage but for a longer time.

Mixed Circuits

Mixed circuits maintain the current that flows through the elements in series and the voltage of the elements in parallel. The equivalent resistance of the circuit is calculated by the sum of all the partial resistances.