Fundamental Electrical Concepts: Voltage, Current, and Resistance

Fundamental Electrical Concepts

Voltage: This is the energy with which a generator is able to push electrons through a circuit (measured in volts).

Intensity (Current): This is the number of electrical charges going through the circuit per unit time (measured in amps).

Resistance: This is the difficulty provided by the material to the passage of electric current (measured in ohms).

Power (Watts): This is the ability of a receiver to perform its function more closely and/or faster (measured in Watts).

Key relationships include:

• $R = V / I$
• $P = V \cdot I$
• $I = V / R$

Circuit Connections

Series Connection

When the elements are connected one after another, the same intensity flows through all components, and the voltage spreads across them.

Parallel Connection

The power is divided between the elements and rejoins at the output. The same voltage is present across all elements, and the intensity is scattered (divided).

Measurement Instruments

• Voltmeter: Measures parallel voltage.
• Ammeter: Measures current in series.
• Ohmmeter: Measures resistance (ideally without voltage applied).
• Wattmeter: Measures power.

Effects of Electrical Current

Thermal Effect (Joule Effect)

When the current intensity increases, heat is generated (e.g., in a stove or oven).

Short Circuit

A short circuit occurs when the electrical power flows from one pole to another without passing through any significant resistance. The resulting heat energy flows so easily that it can burn the surrounding track.

Fuses are used to prevent the destructive effects of a short circuit. These are older protection devices. They are constructed with a material driver of low melting point and are placed at the top of the electrical installation or next to the device/circuit to be protected. If a short circuit occurs, the fuses melt due to the increased temperature, opening the circuit, stopping the flow, and preventing further consequences. Fuses were traditionally placed in a fuse holder.

Magnetic Effect

Every conductor carrying an electric current creates a magnetic field around it, which weakens as the distance increases.

A Coil is formed when an electrical conductor is wound into a spiral shape. If an iron core is placed inside the coil, the electric current circulating in the coil magnetizes it. The magnetic field becomes much more intense with the core present.

An Electromagnet is a temporary artificial magnet; it acts only as long as the electric current flows. It is formed by a coil of copper wire and an iron core.