Electrical components and circuits

Electrical Components Electrical Components and Circuits and Circuits

By By Naaimat MuhammedNaaimat Muhammed

CURRENT CIRCUITS AND CURRENT CIRCUITS AND MEASUREMENTSMEASUREMENTS

The general definition of a circuit is a The general definition of a circuit is a closed path that may be followed by closed path that may be followed by an electric current. an electric current.

GalvanometerGalvanometerA galvanometer is a device with a A galvanometer is a device with a

rotating indicator that will rotate rotating indicator that will rotate from its equilibrium position when a from its equilibrium position when a current passes through it. current passes through it.

A galvanometer has a negligible A galvanometer has a negligible resistance. resistance.

Ampermeter Ampermeter An ampermeter (ammeter) is a galvanometer An ampermeter (ammeter) is a galvanometer

with a calibrated current scale for its indicator with a calibrated current scale for its indicator and a bypass resistor called a shunt.and a bypass resistor called a shunt.

Many ammeters have several selectable shunts Many ammeters have several selectable shunts which provide their corresponding current meter which provide their corresponding current meter ranges.ranges.

Ammeters can be found with calibrated ranges of Ammeters can be found with calibrated ranges of 1 micro-A for full scale deflection up to 1000 A for 1 micro-A for full scale deflection up to 1000 A for full scale deflection, and in multiples of 10 full scale deflection, and in multiples of 10 between these extremes. between these extremes.

VoltmeterVoltmeter A voltmeter is a calibrated galvanometer with a A voltmeter is a calibrated galvanometer with a

series resistor so that the total resistance of the series resistor so that the total resistance of the path is increasedpath is increased..

The galvanometer range is calibrated for the The galvanometer range is calibrated for the current Ig passing through it. current Ig passing through it.

Voltmeters may have more than one calibrated Voltmeters may have more than one calibrated scale which can be selected by changing the scale which can be selected by changing the resistance .resistance .

Current in CircuitCurrent in Circuit Current in a circuit is the flow of the positive charge from a Current in a circuit is the flow of the positive charge from a

high potential (+) to a low potential (-).high potential (+) to a low potential (-). Meters are labeled to indicate the proper direction of Meters are labeled to indicate the proper direction of

current flow through themcurrent flow through them.. Electrical charge will not move through a conducting path Electrical charge will not move through a conducting path

unless there is a potential difference between the ends of unless there is a potential difference between the ends of the conductorsthe conductors

The source of energy in a circuit which provides the energy The source of energy in a circuit which provides the energy to move the charge through the circuit can be a battery, to move the charge through the circuit can be a battery, photocell, or some other power supply. photocell, or some other power supply.

Electrical CircuitElectrical Circuit

An electrical circuit is a circuitous An electrical circuit is a circuitous path of wire and devices .path of wire and devices .

An example of a circuit with a DC. power supply in a An example of a circuit with a DC. power supply in a series with a resistor, a parallel branch with a series with a resistor, a parallel branch with a

resistor and voltmeter, and an ammeterresistor and voltmeter, and an ammeter . .

Basic Electric CircuitBasic Electric CircuitThe flashlight is an example of a basic The flashlight is an example of a basic

electric circuit. electric circuit. It contains a source of electrical It contains a source of electrical

energy (the dry cells in the flashlight), energy (the dry cells in the flashlight), a load (the bulb) that changes the a load (the bulb) that changes the electrical energy into a more useful electrical energy into a more useful form of energy (light), and a switch to form of energy (light), and a switch to control the energy delivered to the control the energy delivered to the load. load.

Laws of ElectricityLaws of Electricity

Ohm’s law describes the relationship among potential, Ohm’s law describes the relationship among potential, resistance and current in a resistive series circuit.resistance and current in a resistive series circuit.

In a series circuit, all circuit elements are connected in In a series circuit, all circuit elements are connected in sequence along a unique path, head to tail, as are the sequence along a unique path, head to tail, as are the battery and three resistors.battery and three resistors.

Ohm’s Law may be written as:Ohm’s Law may be written as:

V = IRV = IR

Diagram for determining Diagram for determining resistance and Voltage in a basic resistance and Voltage in a basic

circuitcircuit

ContinuedContinued

Kirchhoff’s LawKirchhoff’s Law Kirchhoff’s current law states that the Kirchhoff’s current law states that the

algebraic sum of currents around any point algebraic sum of currents around any point in a circuit is zero. in a circuit is zero.

Kirchhoff’s voltage law states that the Kirchhoff’s voltage law states that the algebraic sum of the voltages around a algebraic sum of the voltages around a closed electrical loop is zero. closed electrical loop is zero.

Power LawPower LawThe power law states that the power The power law states that the power

in watts dissipated in a resistive in watts dissipated in a resistive element is given by the product of element is given by the product of the current in amperes and the the current in amperes and the potential difference across the potential difference across the resistance in voltsresistance in volts

P = IVP = IV

Basic Direct Current CircuitsBasic Direct Current Circuits

Parallel CircuitsParallel Circuits

ReferencesReferences ““Direct Current Circuits.” Direct Current Circuits.”

http://pneuma.phys.ualberta.ca/~gingrich/phys395/nothttp://pneuma.phys.ualberta.ca/~gingrich/phys395/notes/node2.htmles/node2.html

““Field effect transistors (FETs) as transducers in Field effect transistors (FETs) as transducers in electrochemical sensors.”electrochemical sensors.”

http://www.ch.pw.edu.pl/~dybko/csrg/isfet/http://www.ch.pw.edu.pl/~dybko/csrg/isfet/chemfet.htmlchemfet.html

Skoog, Holler, and Nieman. Skoog, Holler, and Nieman. Principles of Instrumental Principles of Instrumental AnalysisAnalysis. 5th ed. Orlando: Harcourt Brace & Co., . 5th ed. Orlando: Harcourt Brace & Co., 1998.1998.

Shul’ga AA, Koudelka-Hep M, de Rooij NF, Netchiporouk Shul’ga AA, Koudelka-Hep M, de Rooij NF, Netchiporouk LI. “Glucose sensitive enzyme field effect transistor LI. “Glucose sensitive enzyme field effect transistor using potassium ferricyanide as an oxidizing substrate.” using potassium ferricyanide as an oxidizing substrate.” Analytical ChemistryAnalytical Chemistry. 15 Jan. 1994. . 15 Jan. 1994.