Variable capacitors Variable capacitors are distinguished by the fact that their capacitance can be changed. Basically, there are two most common types of such capacitors named as a trimmer and rotor-stator capacitors. Rotor-Stator Capacitor The rotor-stator type of capacitor comprises two metallic plate sets. The moving plates are attached conjointly …

Read More »## Ohm’s Law | Ohm’s Law Formula

As the voltage increases in a circuit (resistance remaining constant), the current increases by the same amount. Hence, if the voltage is doubled, the current will double. Also, the amount of current in a circuit is inversely proportional to its resistance when the voltage remains unchanged. Stated another way, if …

Read More »## Capacitive Reactance | Reactance of Capacitor

If a sinusoidal voltage is applied to a pure capacitance ( no series or parallel resistance), the current is maximum when the voltage begins to rise from zero.one-quarter a cycle later, the current is zero when the voltage across the capacitor is maximum. This condition, illustrated in figure 1, shows …

Read More »## Inductive Reactance | Reactance of Inductor

Inductive Reactance Opposition to the flow of an alternating current by the inductance of the circuit; equal to 2πfL and measured in ohms. When a changing current flows through an inductor, a self-induced voltage is developed. Its polarity is such that it opposes the change. The emf varies directly with …

Read More »## Electrical Formulas | Electrical Formulas Sheet

A Absolute Permittivity ${{\varepsilon }_{o}}=8.84*{{10}^{-12}}$ Active Power $\text{P=VICos(}\theta \text{) Watt}$ Apparent Power $\text{S=VI volt-amp}$ B C Capacitance $\text{C=}\frac{\text{ }\varepsilon {{\text{ }}_{\text{o}}}\text{ }\varepsilon {{\text{ }}_{\text{r}}}\text{A}}{\text{d}}$ Where, εo= Absolute Permittivity εr= Relative Permittivity A=Plates Area d= distance between plates Conductance $\text{Conductance}=\frac{1}{\text{Resistance}}=\frac{1}{\text{R}}$ Capacitive Reactance ${{\text{X}}_{\text{C}}}\text{=}\frac{1}{2\pi fC}$ Capacitive Susceptance ${{\text{B}}_{\text{C}}}\text{=}\frac{1}{{{\text{X}}_{\text{C}}}}$ Current in Series Circuit …

Read More »## Factors Affecting Capacitance | Dielectric Constant

There are three main factors affecting the capacitance of the capacitors that will be discussed in this tutorial in detail. The SI unit of capacitance is farad, named in honor of the English physicist and chemist Michael Faraday. The unit symbol for the farad is F. capacitance is the ability …

Read More »## Types of Resistors | Power Resistor

Resistor An element used to reduce supply voltages to some desired value or to limit current. A resistor is a small component with two leads. A wide variety of resistors is used in the electronics industry today. Carbon composition resistor The carbon composition resistor is the basic mass-produced resistor of …

Read More »## Nonlinear Resistors | Characteristics Curves of Different Nonlinear Devices

In most circuits, we can assume that resistance is constant with relation to current and voltage. This linear relation can be graphically shown in figure 1. Fig.1: Plot of Linear Relation between Current and Voltage For example, if 3V is applied to a certain resistor and 1A flows, then 6V …

Read More »## Resistor Color Code | Resistor Color Bands

Carbon resistors are color coded- that is, they have several color bands painted around the body near one end- to identify their ohmic values. Other types of resistors are not color-coded; instead, they have their ohmic values and, sometimes, identifying part numbers printed on them. The code has been established by …

Read More »## Resistor Power Rating | Power resistor

The physical size of a resistor is not determined by its resistance but by how much power, or heat, it can dissipate. It electric circuits, the unit of power is the watt (W), named in honor of James Watt. One watt is the power dissipated when one ampere flows under …

Read More »## Source Transformation Example Problems with Solutions

A highly valuable byproduct of Thevenin’s and Norton’s theorem is the technique of source transformation. Source transformation is based upon the observation that if a Thevenin’s network and Norton’s network are both equivalent to a particular source network, then they must also equivalent to each other. This observation allows you …

Read More »## Voltage divider Circuits and Current divider Circuits

In analyzing a series circuit, it becomes necessary to find voltage drop across one or more of the resistances. A simple voltage drop relationship may be obtained by referring to the following figure. The total current is given by, $I=\frac{E}{{{R}_{1}}+{{R}_{2}}+{{R}_{3}}}$ And the voltage drop are given by, ${{V}_{1}}=I{{R}_{1}}=E\frac{{{R}_{1}}}{{{R}_{1}}+{{R}_{2}}+{{R}_{3}}}~~~~\text{ }~~~\left( 1 …

Read More »## Impedance, Inductive Reactance and Capacitive Reactance

Impedance is the combined resistance in the flow of current because of resistive and reactive elements in the circuit. It is measured is ohm and calculated as follows; $Z=R+jX$ Inductive Reactance Consider a sinusoidal current to be flowing in the pure inductance as shown in the following Fig. that is …

Read More »## Power Factor and Power Factor Correction

The ratio of true power to apparent power in an AC Circuit is called the power factor and can be expressed as follows: $PF=\frac{True\text{ Power P}}{Apparent\text{ Power S}}$ It is also defined as the ratio of resistance to the impedance (series circuit): $PF=\frac{\operatorname{Resistance}\text{ R}}{\operatorname{Impedance}\text{ Z}}$ Since R/Z is the …

Read More »## Apparent, Active and Reactive Power

This section covers basic concepts about apparent, active (real) and reactive power which is important ingredients in the analysis of a power system. Consider the general single-phase circuit with a sinusoidal voltage $v={{V}_{m}}sin\left( wt \right)$ applied. A current $i={{I}_{m}}sin(wt\pm \theta )$ results and is leading (θ is positive) for a capacitive …

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