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Chapter 1 & 2 Summary

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OHMS LAW

IRV If R is constant;

V is directly proportional to current

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SERIES CIRCUIT

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PARALLEL CIRCUIT

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Voltage Drop and Voltage Divider

Rule

Only applicable in series circuits ascurrent flowing through the circuits is

the same.

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Current Drop and Current Divider

Rule

Only applicable in parallel circuit asvoltage on each circuits is the same.

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Power and Units

Electrical power can be related by:-

P = V X I (J/s or watt)

P = I2 X R (J/s or watt)

P = V2 / R

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Find:

a) RT

b) IT

c) I1 & I2

d) Power at

each load.

TUTORIAL

5V

2

4 6

I1 I2

5

3

I3

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Direction Rules

Electron Flow

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Magnetic Flux Density

Flux is line of force induced bymagnets.

Magnetic flux density is the amount of

flux passing through a defined areaperpendicular to the direction of flux.

Magnetic flux density can be

represented by Tesla.

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Magnetomotive Force

Magnetomotive force (mmf) is thecause of the existence magnetic flux

of a magnetic circuits.

Where N is the numbers of conductor

turns and I is the current flowingthrough the conductor

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Magnetic Field Strength

Magnetic Field Strength is themagnetomotive force relative to the

mean length of the flux path in meters.

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Flemings Left hand Rule

(Motor Rule) Determines vector of each variables

involved in a motor.

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Factors Affecting

Electromagnetic Strength

Current, I

Flux Density, B

Conductor Length, l

E ti R l ti

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Equation Relating

Electromagnetic Force and

ElectricityForce, F = Flux Density, B X Current, A X

Length, l.

Flux Density, B

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Flemings Right Hand Rule

(Generator Rule) Identifies the vector for each involved

variables for a generator.

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Relationship between

Electromotive Force Electromotive Force (e.m.f) is

generated by the changes of flux

when conductor moves across a

magnetic field. Potential of e.m.f generated is

proportional to flux density, the length

of conductor and speed of conductormoving across a magnetic field,

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Mutual Inductance

The magnetic flux through a circuitrelating to the current in that circuit

and the currents in other nearby

circuits. Mutually induced e.m.f in the second

coil.

The relationship of the current flow infirst circuit and the induced e.m.f in

second circuit is related by :-Where M is the mutual inductancebetween the two circuits (Henries)

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Mutual Inductance in Two

Circuits

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Mutual Inductance

The magnetic field produced by circuit1 will intersect the wire in circuit 2 andcreate current flow.

The induced current flow in circuit 2will have its own magnetic field whichwill interact with the magnetic field ofcircuit 1.

At some point P, the magnetic field willconsist of summation of current flow incircuit 1 and current flow in circuit 2.

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Example

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Example

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Example

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Example

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Example

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Example