Tips on how to do electrical calculations

The importance of electrical calculations in an electrical installation or for any other area of ​​electrical is necessary. These calculations include four basic electrical quantities, which are defined as electrical current, electrical voltage, electrical power and electrical resistance. In this article we will show the electrical calculations most used by professionals in the electrical field and show the importance of knowing them. Come on!

Ohms Law

Ohm’s law is one of the most important laws of electricity, it is one of the most applied formulas in electrical calculations! Ohms’ law is the basis for electrical calculations and involves four electrical quantities, namely:

Electric tension

The electrical voltage can be defined as the force necessary for the electrons to move because whenever there are different electrical potentials, the difference between them will cause the electrons to move. For example, outlets, batteries and supplies. The electrical voltage, similarly called the potential difference, characterizes the differential of the electrical potential between two points. It is, therefore, the force resulting from the movement of electrons in a given circuit. The electrical voltage is measured in units called volts (V), and the electrical voltage is represented in the formulas by the letter V or the letter U.

Electric current

The electrical current is caused by a difference in electrical potential, that is, the flow of electricity represents the number of charges that pass through a certain path. Thus, the electric current can also be defined by the design of the electric field, which when considering a positive and a negative charge, there is a field guiding from positive to negative charge. The electric current is measured by a unit called an amp (A). In the formulas, the indication of the current quantity is with the letter (I).

Electrical resistance

The electrical resistance is the opposition that material offers the passage of electric current, in other words refers to the difficulty that the current is to go through a particular body. The unit of electrical resistance is the ohm, which is the Greek letter omega (Ω). In formulas, the electrical resistance is represented by the letter R.

Electric power

The electric power is the ability with which a given load is to convert electrical energy into another type of energy such as thermal energy, light, sound and others. In addition, we can mention that there are three types of electrical power, which is reactive, active and apparent power. The unit of measurement used for electrical power is watt (W). In formulas, electrical power is represented by the letter P.

Ohm’s law is very simple, when we have the value of two of these quantities, it is possible to find the third variable, for that it is enough to use the appropriate formula.

Ohms law formulas, basis for electrical calculations.

Kirchhoff’s laws

Kirchhoff’s laws are fundamental to perform series, parallel or mixed circuit analysis, as they are directly related to the two main electrical quantities, which is the electric current and the electrical voltage.

Kirchhoff’s first law

Kirchhoff’s first law, also known as the law of currents or the law of nodes, is related to the electric current in a node. She says that the result of the sum of the electric currents in a node is always equal to zero, so the node does not accumulate charge. Since the node is a point that the current divides having two or more paths to go through the circuit and the sum of all currents that enter a node is equal to the sum of all currents that leave the node.

Kirchhoff’s first law.

Kirchhoff’s second law

Kirchhoff’s second law, also known as the tension law or the mesh law, is related to the electrical voltage in a mesh. Kirchhoff’s second law says that the result of the sum of the electrical voltages in a grid is equal to zero. It is important to highlight that the mesh can be defined by a closed circuit, through which a current circulates, so that in a circuit it can have more than one mesh.

Kirchhoff’s second law.

Voltage Divider

Electric voltage divider or also known by some as resistance divider, is a technique applied in series circuit, to obtain an electrical output voltage that is represented by Vout, from another electrical input voltage that is represented by Vin. Voltage divider is normally used to obtain a reference voltage, as we can see in the following formula:

Voltage divider, series circuit.

Current Divider

Electric current divider, is a parallel circuit analysis technique, used to calculate the current flowing in a given path. To apply this method, it is not necessary to have the value of the electrical voltage at any point in the circuit or the electrical power of the loads, but it is necessary to have the current entering the node and the value of the resistances or impedances in parallel, as we can see in formula below.

Current Divider, parallel circuit.

Final considerations:

We have seen in this article some formulas for electrical calculations, but it is of great importance to highlight that these are not the only formulas or analyzes that we have, as we also have Norton’s law, Thévenin, nodal analysis and superposition, which are fundamental for any circuit analysis . Below is a video that shows in detail how to perform the resistor association calculations in a mixed circuit.