Understanding Electric Current and Magnetism

Fundamentals of Electric Current

Electric current is the movement of electrons through a conductor. Its basic magnitudes are:

• Voltage (V): Also known as potential difference between two points in a circuit, it indicates the energy difference between points. Its unit of measurement is the volt (V).
• Resistance (R): The resistance of a material indicates its opposition to the electric current passing through it. It is measured in ohms (Ω).
• Current Intensity (I): This expresses the amount of electric charge flowing through a section of the circuit per second. It is measured in amperes (A).

Ohm's Law and Electrical Energy

Ohm's Law relates the current intensity with two dependent variables: voltage and resistance. Electrical Energy (E) consumed by a receptor connected to a circuit is used to produce various effects, such as heat, movement, and light. The unit of measurement is the joule (J).

Electric Power (P) expresses the energy that a receptor consumes every second and is calculated according to the basic characteristics of the receptors. It is measured in watts (W).

Types of Electric Current

Direct Current (DC)

In Direct Current, the flow is always in the same direction (from the negative to the positive pole), such as in a battery. The voltage of direct current is constant, and its value is usually a few volts. The intensity is also constant, often having small values expressed in milliamps. Devices powered by direct current include radios, mobile phones, and computers.

Alternating Current (AC)

In Alternating Current, the electrons change their direction of flow. This is the electricity produced by power plant alternators. The voltage is several hundred volts, and the current value may be several amps. It is used in lighting circuits, appliances, and machines.

Magnetism and Magnetic Materials

Some materials called magnets can attract pieces of iron; this property is known as magnetism. In any magnet, there are two poles: the north pole (N) and the south pole (S).

Classification of Magnets

• Natural magnets: These are iron ores, such as magnetite, found in nature which possess magnetic properties.
• Artificial magnets: These are materials that acquire magnetic properties through different procedures, for example, when rubbed with another magnet.

Applications of Magnetism

Magnetism is used in appliances and electrical devices such as loudspeakers, the Morse telegraph, or doorbells. Other electronic devices, such as relays, use magnetism to control the flow of electric current. In many industrial processes, it is used for the restraint or movement of iron pieces, or the separation of iron and steel materials.