ohms law - intro

7/31/2019 Ohms Law - Intro

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Introduction to Ohms Law
http://en.wikipedia.org/wiki/File:Ohm3.gif


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Introduction


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Introduction

Why do you need to be here?Foundation for any electrical studiesSafetywhen working with electricityTroubleshooting electrical circuitsDesign of electrical circuits


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Introduction

Georg Simon Ohm16 March 1789 6 July 1854German PhysicistUsing equipment of his own creation,

Ohm determined that there is a directproportionality between the potential

difference (voltage) applied across aconductor and the resultant electriccurrent.
http://en.wikipedia.org/wiki/File:Ohm3.gif


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The flow of valence (or outer) electrons between

atoms in a conductor

Produced by potential difference

Fundamental Concepts & Terms

Electricity


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Flow of electrons from atom to atom

Measured in amps (a)

Current



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Electrical pressure or force with whichelectrons move

Measured in volts (v)

Voltage



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The opposition an element or material has tothe flow of electrons

Measured in ohms ()

Resistance



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Plumbing Analogy


Pressure = Voltage

Flow = Current

Reducer = Resistance

The pressure (voltage) changes across the reducer (resistor)

The flow (current) is the same throughout


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Name Abbr. Measurement SymbolVoltage E Volts V

Resistance R Ohms

Amperage I Amps A


E = Electromotive Force (EMF)

I = Intensity


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Series CircuitAn electrical circuit in which all loads are arranged

in a chain, so the current has only one path to take.

In these circuits Voltage is different at variouspoints, while the Current is the same


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Parallel CircuitAn electrical circuit in which the loads are

arranged with their heads connected together, andtheir tails connected together, causing the current

to follow multiple paths. In these circuits Current is different at various

points, while the Voltage is the same

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Series-Parallel CircuitAn electrical circuit in which the some of the loads

are arranged in a chain with other loads that havetheir heads connected together, and their tails

connected together. In these circuits Voltage and Current are both

variable


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Oh L


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One volt (E) will push one amp of current (I) through oneohm () of resistance (R)

Ohms Law In an electrical circuit, the current passing through a

conductor between two points is proportional to thepotentialdifference (i.e. voltage drop or voltage) across the two points, andinversely proportional to the resistance between them.

Ohms Law

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I =E

RR =

E

IE = IR

Ohms Law

Oh L


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Ohms Law

Current is 5 amps & Resistance is 200 ohms, then Voltage is _______ volts.

Current is 10 amps & Voltage is 440 volts, then Resistance is _______ ohms.

Resistance is 150 ohms & Voltage is 600 volts, then Current is _______ amps

1,000

44

4

Oh L


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Any Questions So far?

Ohms Law

ohms law - intro

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