These problems are from Section 17.4. For the fifth one (SV 17.12), you might find yourself with two equations involving length and area of the wire: the given mass gives you L*A, and the resistance gives you L/A. Multiply those two equations together and it eliminates A.
2 comments:
Hello,
Quick question:
For Exercise 17.4 on page 580, why does the drift speed decrease as the temperature rises?
Well, I'm afraid the book doesn't provide enough information to make that a well-posed question, but we can try to speculate what the author had in mind. We know that when the temperature increases, the resistance increases, but to say anything about drift speed, you have to know the current (and carrier density and cross section of the wire). I don't suppose that the latter two would change, and so if the current is constant, the drift speed wouldn't change either. Maybe the authors meant to tell us that there is a fixed voltage across the resistance thermomenter? Then as the temperature increases, the resistance increases, so the current decreases (I=V/R) which would make the drift speed decrease.
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