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# Basic Electrical

## Ohms Law and Power in Electrical Circuits

This module will enable readers to use Ohm’s Law and electric power formulas to determine the voltage, current, resistance and power in a basic DC circuit. Objective Learner will be able to: Use Ohm’s Law to determine voltage, current, or resistance Define Energy and Power Calculate Power in a basic …

## Resistor Color Code and Resistor Tolerance Explained

As you know, a resistor is a component that is designed to provide specific amount of resistance. Resistors are classified as being either fixed or variable. A FIXED RESISTOR is one that has specific ohmic value that cannot be changed by the user. A VARIABLE RESISTOR is one that can …

## Inductor and Capacitor Basics

The ideal resistor was a useful approximation of many practical electrical devices. However, in addition to resistance, which always dissipates energy, an electric circuit may also exhibit capacitance and inductance, which act to store and release energy, in the same way that an expansion tank and flywheel, respectively, act in …

## Hybrid Parameters of Two Port Network

For analyzing circuits containing active devices such as transistors, it is more convenient to think of the input terminals of a four-terminal coupling network as a Thévenin-equivalent voltage source and the output terminals as a Norton-equivalent current source. We then describe the coupling network in terms of four hybrid parameters …

We can represent the generalized coupling network by the π-network shown with dotted lines in Figure 1. It is simpler to work with admittances when we encounter a coupling network in the form of a π-network, which is a dual for a T-network. Although the resulting short-circuit admittance parameters (y-parameters) …

## Open-Circuit Impedance Parameters

To define the composition of a four-terminal, two-port network, we need four parameters. The test circuit of Figure 1 gives a set of parameters called the open-circuit impedance parameters (z-parameters) of the network. Figure 1 Determining open-circuit impedance parameters We start by opening the right-hand switch in Figure 1 so …

## Impedance in Series and Parallel

Resistance and impedance both represent opposition to electric current. However, resistance opposes both direct and alternating current, while the reactance component of impedance opposes only changing current. Calculations for DC circuits can be done with scalar quantities and ordinary algebra. But impedance is a phasor quantity in AC circuits, and …

## Parallel Circuit Characteristics

Parallel Circuit Definition Resistors are said to be connected in parallel when the same voltage appears across every component. With different resistance values, different currents flow through each resistor. Resistance, Inductance, and Capacitance in Parallel Circuit The characteristic of a parallel circuit is that the same voltage appears across all parallel branches. We use …

## Phasor Diagram and Phasor Algebra used in AC Circuits

Figure 1 shows a simple AC series circuit containing resistance and inductance. The sine-wave voltage source causes a sine wave of current to flow in the circuit. Since all the components are connected in series, the current in the inductance and the current in the resistance must have the same …

## Instantaneous Current in an Ideal Inductor

In the circuit of Figure 1, we assume that the inductor has negligible resistance. To satisfy Kirchhoff’s voltage law, at every instant the inductive voltage across the coil in Figure 1 must exactly equal the applied voltage. Hence, ${{v}_{L}}=e={{E}_{m}}\sin \omega t$ Figure 1 Inductance in an ac circuit If …

## Instantaneous Current in a Capacitor

If we connect a capacitor across a sine-wave voltage source, as in Figure 1, Kirchhoff’s voltage law requires the voltage across the capacitor to be exactly the same as the applied voltage at every instant. The voltage across a capacitor can change only if the capacitor charges or discharges. Consequently, …

## Periodic Wave

Although the sine wave is by far the most important AC waveform, there are many other types of periodic waves. In electric circuits, a periodic wave is any time-varying quantity, such as voltage, current, or power that continually repeats exactly the same sequence of values with each cycle taking exactly …

## RMS Value of a Sine Wave

All electric circuits convert electric energy into some other form of energy, such as heat, light, or mechanical energy. For many of these energy conversions, it does not matter whether the energy source for the circuit produces direct current or alternating current. Therefore, we find equivalent steady-state values for alternating …