Brown Cp Flashcards

1
Q

Interference is

A

Any electrical disturbance on a metallic structure caused by stray current

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2
Q

Stray current is

A

Current flowing on a structure that it is not part of the intended electrical circuit

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3
Q

Dynamic stray currents vary in magnitude and often in direction. These currents can be?

A

Man made or natural in origin

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4
Q

Man made dynamic stray currents come from sources such as

A

Mine railroads,rail transit system and arc welding operations

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5
Q

Tellurium currents are

A

Naturally occurring dynamic stray currents caused by earths magnetic field by sun spot activity

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6
Q

Steady state or static stray current

A

Maintain constant magnitude and direction

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7
Q

Dynamic stray currents are manifested by

A

Fluctuations in structure-electrolyte potentials readings

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8
Q

Electrons are

A

Particles that carry a negative charge…….also help to hold matter together (kind of like midterm)

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9
Q

Voltage (joule/coulomb) or potential

A

A electromotive force or a difference in potential expressed in volts

Voltage is the energy that puts charges in motion

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10
Q

Corrosion uses these units of measure

A

Volts
Millivolts
Microvolt a

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11
Q

1,000 volts is

A

1 kilovolt

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12
Q

1.000 volts equals

A

1000 millivolts

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13
Q

0.100 is

A

100 millivolts

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14
Q

0.010 volt is

A

10 millivolts

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15
Q

0.001 volt is

A

1 millivolts

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16
Q

0.000001 is

A

1 microvolt

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17
Q

EMF is

A

Electromotive force any voltage

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18
Q

E or e is

A

Voltage across a source of electrical energy (battery,pipe-to soil potential )

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19
Q

V or v is

A

Voltage across a sink of electrical energy (resistor)

20
Q

Current is

A

The flow of charges along a conducting path is measured in amperes, ……..frequently abbreviated as amps

21
Q

Ampere is

A

The common unit of current=flow rate of charge of 1 coulomb per second

1 coulomb is the unit of charge carried by 6.24 X 10(18) electron charges

22
Q

1,000 amperes is 1….

A

1 kilo ampere

23
Q

1.000 is

A

1000 milliamperes

24
Q

0.100 is

A

100 milliamperes

25
Q

0.010 amperes is

A

10 milliamperes

26
Q

0.001 ampere is

A

1 milliamperes

27
Q

0.000001 amperes is

A

1 micro ampere

28
Q

Common symbols for current flow are

A

I, A, mA

uA=micro amperes

29
Q

Resistance is

A

The opposition that charges encounter when moving throu a material

30
Q

The ohm is the common unit of resistance ……letter for ohm is

A

R or r also the Greek letter omega

31
Q

Resistivity is

A

The resistance of a conductor of unit length and cross-sectional area ….symbol is Greek letter p

32
Q

Resistivity is constant for a given material and is computed by the formula

A

P=RxA/L

p= Greek letter for resistivity
R=resistance in ohm’s
A=cross sectional area in cm2(centimeter squared)
L=length in cm

33
Q

Resistance to current flow is lowest

A

Low resistivity ( high conductivity) media
Short length of current flow
Large area of current flow

34
Q

Resistance will be greatest for:

A

High-resistivity (low conductivity) media
Long path length for current flow
Small cross sectional area of current flow

35
Q

The electric circuit is

A

The path followed by an electric current

36
Q

Electrical laws govern the relationship in

A

Electric circuits

37
Q

Ohm’s law is

(1v will create 1 current ampere in a circuit having a resistance of 1 ohm

A

A relationship between the ratio of voltage and current to the resistance of a circuit

38
Q

Power is

A

The rate at which energy is used by an electrical device

39
Q

Power is measured in

A

Watts

P=EI
P=I2R

40
Q

Kirchhoffs voltage law

A

The sums of the source voltages around any closed loop circuit is equal to the sum of the voltage drops across the resistances in that loop

41
Q

Kirchhoffs current law

A

The law states as much current flows away from a point as flows towards it

42
Q

In a series circuit

A

The same current flows in an individual, consecutive path from the source of the voltage through the various loads and back to the source

Current is the same everywhere

Sum of the voltage add up the the voltage source

Total resistance of a series circuit equals the sum of the individual resistance

43
Q

In a parallel circuit….the current..

A

Divides into a number of separate branches

The current in each branch maybe different

Each branch may have deferent resistance

If you can trace more than one path for current to flow through the circuit…..it’s a parallel circuit

Total current flowing into and out of the junction point of the branches equals the sum of branch currents (kirchhoffs current law)

44
Q

Ohm’s law

A

V=IR

I=V/R

R=V/I

45
Q

Unit of measure used in conjunction

A

Volt, Ampere,Olm’s

46
Q

Parallel circuit

A

Total of current in each leg is equal to the total current

B: voltage across each resistor is equal to net supply voltage

47
Q

Metals that corrode under low and high pH levels are termed

A

Amphoteric