12A
YOUR ANSWER:
The two types of resistors are metallic and wire-wound.
(From P1-17A)
Shame. A wire-round resistor is an example of a metallic-type resistor. Also, an axial-lead resistor is an
example of a nonmetallic type of resistor. Go back to Page 1-17A and choose the correct answer.
12B
YOUR ANSWER:
Melting point, cost, and the ability to be fused.
(From P1-20B)
Right. That's three of the five items to consider when selecting a conductor. The next item is the weight.
Today, with more and more electronic gear being put in aircraft, weight has become a very important item.
Copper is the second best metallic conductor and aluminum is the fourth best, but when considering a conductor
to use in aircraft, the lighter weight of aluminum more than offsets the difference in conductivity.
The last item is elasticity (good spring action). Some conductor applications such as meter springs and
switch spring contacts require a material with good elasticity. Phosphor bronze is a good example of this type of
elasticity. So far, we have talked about conductors and the five factors affecting the choice of a conductor. We
have also learned about the four items that determine the resistance of a conductor and, finally, the meaning of the
specific resistance of a material. Let's take a check on how much you have learned.
Which of the following statements are correct?
The specific resistance of a material is the
resistance of a unit volume of that material
at a temperature of 20 degrees centigrade.
Page 1-5B
The five items affecting the choice of a con-
ductor are cost, ability to be fused or soldered,
melting point, weight, and elasticity.
Page 1-14B
The four factors determining the resistance of
a conductor are the type of material, temperature,
length, and the cross-sectional area.
Page 1-18A
All the above statements are correct.
Page 1-19B
IT0340
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