Category: Electrical Circuits & Networks
-
Types of Resistors
Resistors perform two basic functions in a circuit: they limit current flow and set voltage levels within a circuit. We have various kinds of resistors e.g. fixed resistors, variable resistors, digitally adjustable resistors, photoresistors, fusible resistors, etc. Generally, resistors can be broadly categorized as: Fixed Resistors Fixed resistors are those whose value cannot be changed…
-
Alternating Currents and Voltages
Alternating current generator Let’s consider a signal turn coil rotating freely at a constant angular velocity symmetrically between the poles of a magnet as illustrated below: The ends of the loop are terminated in slip rings. As the loop rotates, side A will have an emf induced first in one direction and then in the…
-
AC Circuits with Resistors, Inductors and Capacitors
Purely Resistive Circuits In resistive elements the current and voltage are in phase. Purely Capacitive Circuits In capacitive circuits, the current leads the voltage by 90°. Purely Inductive Circuits In inductive circuits the current lags the voltage by 90°. Related: Inductance R, L, and C in Series Because the voltages and the currents are not…
-
DC Networks Theorems
The laws that determine the currents and voltage drops in DC networks: In addition to the above laws, we have several circuit theorems used to solve problems in electrical circuits and they include: Kirchhoff’s Laws Kirchhoff’s laws states that : Current law – At any junction in an electric circuit, the total current flowing towards…
-
Key Facts about Resistors, Resistor Colour Codes and Resistor Tolerance
Resistors perform two basic functions in electronics: These two Resistor features of current limiting and voltage setting are implemented in various ways in electronics as listed below: The figure below shows how a resistor is used as a current limiter: The figure below demonstrates how a resistor is used to create a voltage divider capable…
-
Inductance
What is Inductance? Inductance is the property of a circuit whereby there is an emf induced into the circuit by the change of flux linkages produced by a current change. When the emf is induced in the same circuit as that which the current is changing, the property is called self-inductance, L. When the emf…
-
Capacitors, Capacitance and Charge
Introduction to Capacitors A capacitor is an electrical device that is used to store electrical energy. A capacitor consists of two metal plates separated by an insulator called a dielectric. It stores electricity in the form of an excess of electrons on one plate and a deficiency on the other. In this state, the capacitor…
-
Series and Parallel Circuits
Series Circuits The figure below shows three resistors R1, R2, and R3 connected end to end i.e. in series with a battery source of V volts. Since the circuit is closed, a current I flow and the voltage across each resistor may be determined from the voltmeter readings V1, V2, and V3. In a series…
-
Root-mean-square (r.m.s.) value
We know that a current passing through a resistance has a heating effect, the magnitude of which we measure in watts, that is power is given by This shows that power (or heat) dissipated in a resistance is proportional to either square of the current or the voltage. Related: The Basics of Electric Circuits Consider…
-
Resistance and Resistivity
The resistance of an electrical conductor depends on 4 factors, namely: The resistance, R, is directly proportional to length L of a conductor. Resistance, R, is inversely proportional to cross-sectional area a, of a conductor. Because R is proportional to L and, R is proportional to By inserting a constant of proportionality into this relationship,…