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# Basic Electrical

## 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 …

## Energy Stored in an Inductor

If we connect an ideal inductor to a voltage source having no internal resistance, the voltage across the inductance must remain equal to the applied voltage. Therefore, the current rises at a constant rate, as shown in Figure 1(b). The source supplies electrical energy to the ideal inductor at the …

## Resistance Measurement Methods

Low Resistance Measurement We can determine an unknown resistance in Figure 1 by applying Ohm’s law to the readings obtained from the voltmeter and ammeter. This method requires that the unknown resistance is connected into a special circuit with two separate meters. This method is useful for measuring very low …

## What is Frequency Response | Basics

The reaction of a circuit has to change in frequency is referred to as its Frequency Response. For example, consider the parallel RLC circuit shown in Figure 1. If the operating frequency of the circuit increases, Here’s what happens: • The reactance of the inductor increases because of XL=2πfL. The …

## AC Waveform & AC Circuit Theory

Generally, the term Alternating Current (AC) is used to describe any current that periodically changes direction. For example, take a look at the circuit current time relationship as shown in Figure 1. The horizontal axis of the graph is used to represent time (t). The vertical axis of the graph …

## Effect of Temperature on Resistance | Temperature Coefficient of Resistance

Checking the voltage/current (V/I) ratio of conductors at various temperatures shows that the resistance of most conducting materials increases linearly with temperature except at very hot or very cold temperatures. Temperature has little effect on the resistance of some alloys, such as constantan. For a few materials, including carbon and …

## Resonance in Series and Parallel RLC Circuit

In any AC circuit consisting of resistors, capacitors, and inductors, either in series or in parallel, a condition can happen in which the reactive power of the capacitors and of the inductors become equal. This condition is called resonance. Simultaneous with the capacitive reactive power and the inductive reactive power being …

## Phase Relationships in AC Circuits | Phase Difference | Phase Shift

Phase Difference When we have two sine waves with the same frequency, the duration of one cycle is the same for both. Nonetheless, irrespective of their peak values, there are two possibilities: 1. The two waveforms reach their maximum values (and accordingly their minimum values) at the same instant. In this …

## Relationship between Voltage Current and Resistance

The fundamental relationship between resistance, voltage, and current can be expressed using Ohm’s law. Mathematically, it is expressed as: $V=IR$ Where, V is measured in Volts I is measured in Amps R is measured in Ohms Electric Current The electric current is a measure of the rate of flow (i.e., …