3-A-003: Materials
3-3A1:
What metal is usually employed as a sacrificial anode for corrosion control purposes?
Zinc bar.
Platinum bushing.
Lead bar.
Brass rod.
3-3A2:
What is the relative dielectric constant for air?
1
2
4
0
3-3A3:
Which metal object may be least affected by galvanic corrosion when submerged in seawater?
Stainless steel propeller shaft.
Aluminum outdrive.
Bronze through-hull.
Exposed lead keel.
3-3A4:
Skin effect is the phenomenon where:
RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases.
RF current flows in a thin layer of the conductor, closer to the surface, as frequency decreases.
Thermal effects on the surface of the conductor increase the impedance.
Thermal effects on the surface of the conductor decrease the impedance.
3-3A5:
Corrosion resulting from electric current flow between dissimilar metals is called:
Galvanic corrosion.
Electrolysis.
Stray current corrosion.
Oxygen starvation corrosion.
3-3A6:
Which of these will be most useful for insulation at UHF frequencies?
Mica.
Rubber.
Wax impregnated paper.
Lead.
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Color key:
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● = Unseen
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● = Weak
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● = Review
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● = Learned
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● = Incorrect answer
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