Question about: conductivity: gold, silver, copper, and aluminum.

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Duuk

Duuk

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Location
Texas
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Journeyman
Good evening everyone,

On Mike’s quizzes under the theory this question arose.

Reference: Unit 9 - Electrical Formulas - 9.3 Conductance

The best conductors, in order of their conductivity, are: gold, silver, copper, and aluminum.

The correct answer is False.

I thought this would be true.

Please help me understand.

Thanks for your time,
 
Dennis Alwon

Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
Silver is #1

Conductivity refers to the ability of a material to transmit energy. There are different types of conductivity, including electrical, thermal, and acoustical conductivity. The most electrically conductive element is silver, followed by copper and gold. Silver also has the highest thermal conductivity of any element and the highest light reflectance. Although it is the best conductor, copper and gold are used more often in electrical applications because copper is less expensive and gold has a much higher corrosion resistance. Because silver tarnishes, it is less desirable for high frequencies because the exterior surface becomes less conductive.


As to why silver is the best conductor, the answer is that its electrons are freer to move than those of the other elements. This has to do with its valence and crystal structure.
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Duuk

Duuk

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Location
Texas
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Journeyman
GoldDigger said:
We gold plate contact surfaces not because of the high conductivity of gold, but because of its resistance to corrosion. This is particularly important when switching low voltages which cannot break down a thin insulating layer.
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Thanks for your reply, have a great weekend! 🙏
 
G

gar

Senior Member
Location
Ann Arbor, Michigan
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EE
221119-231 EDT

Gold should plated over nickel because gold is pourus, and nickel is not. If you use gold only, then you probably want gold thicker than at least 50 millionths.

Gold contacts for low voltage signal circuits are a great advantage at little cost.

However, there are some environments where gold is even a problem. Here a reed switch may be a better choice.

.
 
Duuk

Duuk

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Location
Texas
Occupation
Journeyman
GoldDigger said:
We gold plate contact surfaces not because of the high conductivity of gold, but because of its resistance to corrosion. This is particularly important when switching low voltages which cannot break down a thin insulating layer.
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Thank you sir. 🙏
 
Duuk

Duuk

Member
Location
Texas
Occupation
Journeyman
gar said:
221119-231 EDT

Gold should plated over nickel because gold is pourus, and nickel is not. If you use gold only, then you probably want gold thicker than at least 50 millionths.

Gold contacts for low voltage signal circuits are a great advantage at little cost.

However, there are some environments where gold is even a problem. Here a reed switch may be a better choice.

.
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Thanks 🙏 “reed switch” don’t understand.
 
E

EJPHI

Member
Location
Northern California
We often silver plate RF feed elements because in the real world everything oxidizes. Turns out that Silver oxide has about 90% of the conductivity of Silver. Copper oxide is has about 50% the conductivity of Copper. This is a big deal in the RF world because of skin effect.

Nickel is a great plating intermediary, but it is too lossy for RF.
 
B

Barney B

Senior Member
Location
Hurst, TX
Occupation
Electrical Instructor/Trainer
EJPHI said:
We often silver plate RF feed elements because in the real world everything oxidizes. Turns out that Silver oxide has about 90% of the conductivity of Silver. Copper oxide is has about 50% the conductivity of Copper. This is a big deal in the RF world because of skin effect.

Nickel is a great plating intermediary, but it is too lossy for RF.
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And aluminum oxide is an insulator.
 
Speedskater

Speedskater

Senior Member
Location
Cleveland, Ohio
Occupation
retired broadcast, audio and industrial R&D engineering
Electrical conductivity only matters when the wires have exactly the same diameter and length. Audiophiles get sold on Silver wires all the time.
 
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