Question

Please confim that your test consists of 7 pages. There are 4 problems (partial/full credit). Questions 5-13 are multiple choice (no partial credit). Some constants, equations, and a periodic table are given on page 7. 2. (A) (6 pts) The electrical resistivity of copper (Cu) at room temperature is $17.2 \times 10^{-9}$ ?-m. Suppose a copper cable 1 m long consists of three strands of wire each 250 µm in diameter. What is the room-temperature resistance of the cable? (B) (3 pts) In use, the temperature of the wire increases to 50 °C. Would you expect that the resistance of the cable will increase, decrease, or stay the same as at room temperature? Briefly justify your answer. (C) (3 pts) To slightly increase the yield strength, suppose the copper cable is alloyed with 5 at% Ag. The electrical resistivity of silver (Ag) at room temperature is $15.9 \times 10^{-9}$ ?-m. Would you expect that the resistance of the cable will increase, decrease, or stay the same relative to the pure copper cable? Briefly justify your answer.

          Please confim that your test consists of 7 pages. There are 4 problems (partial/full credit). Questions 5-13
are multiple choice (no partial credit). Some constants, equations, and a periodic table are given on page 7.
2. (A) (6 pts) The electrical resistivity of copper (Cu) at room temperature is $17.2 \times 10^{-9}$
?-m. Suppose a copper cable 1 m long consists of three strands of wire each 250 µm in
diameter. What is the room-temperature resistance of the cable?
(B) (3 pts) In use, the temperature of the wire increases to 50 °C. Would you expect
that the resistance of the cable will increase, decrease, or stay the same as at room
temperature? Briefly justify your answer.
(C) (3 pts) To slightly increase the yield strength, suppose the copper cable is alloyed
with 5 at% Ag. The electrical resistivity of silver (Ag) at room temperature is $15.9 \times 10^{-9}$
?-m. Would you expect that the resistance of the cable will increase, decrease, or stay
the same relative to the pure copper cable? Briefly justify your answer.

$Please confim that your test consists of 7 pages. There are 4 problems (partial/full credit). Questions 5-13 are multiple choice (no partial credit). Some constants, equations, and a periodic table are given on page 7. 2. (A) (6 pts) The electrical resistivity of copper (Cu) at room temperature is 17.2 × 10^-9 ?-m. Suppose a copper cable 1 m long consists of three strands of wire each 250 µm in diameter. What is the room-temperature resistance of the cable? (B) (3 pts) In use, the temperature of the wire increases to 50 °C. Would you expect that the resistance of the cable will increase, decrease, or stay the same as at room temperature? Briefly justify your answer. (C) (3 pts) To slightly increase the yield strength, suppose the copper cable is alloyed with 5 at% Ag. The electrical resistivity of silver (Ag) at room temperature is $15.9 \times 10^{-9}$ ?-m. Would you expect that the resistance of the cable will increase, decrease, or stay the same relative to the pure copper cable? Briefly justify your answer.$

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