What is electrical circuit theory?
- Voltage Source
- Electrical Path
The potential difference between the positive (+) and negative (-) terminals of a voltage source introduces energy into a circuit. The main difference between AC and DC voltage sources is how the current flows. AC sources generate voltages that vary sinusoidally, implying that the current reverses direction on a regular basis. Grid power or generators are two examples. DC sources, on the other hand, generate current that flows in only one direction. Batteries provide direct current voltage.
Current flow via a circuit is facilitated by a conductive route, often known as a conductor. These parts, such as copper wires, lead solder, or metallic traces on a printed circuit board, have very low current resistance (PCB). Additionally, conductors aid in the tying of several parts to a single function.
Any device that uses power in a circuit is referred to as a load. It might be an LED, a motor, or a siren, among other things. The conductor itself acts as the load in a short circuit, producing heat and dissipating electrical power.
Electrical Circuit Analysis: Component Types
In electrical circuits, active components control the flow of current. These components can amplify current, inject it into a circuit, or generate a power gain. Active components include transistors, thyristors, and triode vacuum tubes. Electromechanical components, such as DC motors or relays, use electrical current or voltage in a circuit to perform a mechanical function. Voltage is used to actuate a set of mechanical contacts in the case of electromechanical solenoids by varying the inductance in its coil.
Circuit Parameters in Electrical Circuit Analysis
The most important parameters of electrical circuits are current and voltage. Resistance, inductance, and capacitance are also important characteristics of electrical components.
The flow of electrons through a circuit is referred to as electrical current. Ampere is the unit of measurement for current (A). As previously stated, the current can be either AC or DC. The current flowing through a circuit can be calculated using Ohm's law, which states that the current between any two points is proportional to the potential difference between them.
I = V/R is the equation (Where I is current, V is voltage, and R is resistance).
In practice, we can use a digital multimeter to determine the current in a circuit.
Kirchhoff's Current Law (KCL)
An electrical current always flows in loops around a circuit, starting and ending at the same point, according to Kirchhoff's current law. Furthermore, the current entering the circuit is the same as the current leaving the circuit (1). Similarly, the sum of all currents entering and exiting the circuit at any given time is zero (2). These statements can be expressed mathematically using the following equations:
IOUT = IIN —————————————— (1)
IIN + (-IOUT) —————————————— (2)
The potential difference between any two points in an electrical circuit is referred to as voltage (V) or electromotive force (E). The Volt is the unit of measurement. Voltage, like current, can be AC or DC. Voltage can also be calculated using Ohm's Law and the formula V = IR (Where V is voltage, I is current, and R is resistance).
Kirchhoff's Voltage Law (KVL)
Kirchhoff's voltage law states that the sum of voltages around closed circuits is always zero, i.e., V = 0.
This can be expressed mathematically as:
V1 + V2 + V3 + ……Vn = 0 —————————————— (3)
The ability of a component to resist the flow of electrical current through a circuit is referred to as resistance. Ohms (Greek symbol: ) are the unit of measurement. Ohm's Law states that a conductor's resistance is the ratio of the voltage (V) flowing across it to the current (I) flowing through it.
R = V/I in mathematics (Where R is resistance, V is voltage, and I is current).
Except for superconductors, every component has varying degrees of resistance. However, resistors are specifically designed for this purpose. They are passive, two-terminal components with a range of resistances. To identify the resistances and tolerances they offer, several resistor types are designated with color codes.
When an electrical current passes through a conductor, it has a tendency to produce a magnetic field. The magnitude of the current directly relates to the strength of the produced magnetic field. Inductance is measured in Henrys (H), which bears the name of the American scientist Joseph Henry who discovered it. Inductors, also known as chokes or coils, are straightforward passive parts that, when an electrical current passes through them, can store energy in the form of magnetism. When an electrical current is applied, a conductor wound into a coil generates a magnetic field in the opposite direction. The following formula can be used to calculate inductance in an electrical circuit:
L = V/(di/dt) (where L is inductance, V is potential difference across the coil, and di/dt is current rate of change in A/s).
Capacitance is a circuit element's ability to store an electrical charge when there is a potential difference between its terminals. The Farad is the unit of capacitance, named after Michael Faraday, the scientist who discovered electromagnetic induction. We can use the following formula to calculate the capacitance of a component in an electrical circuit:
C = Q/V (Where C is the capacitance in coulombs, Q is the charge, and V is the potential difference).