A copper wire has a resistance of 0.6 ohm.
Another copper wire of the same mass as the
first one is double in length of the first. Find
the resistance of the second wire.
Answers
Answer:
If we view this question objectively we have troubles because too many details are ignored. We learn the wire is copper but are the two wires identical copper with identical preparation? Copper can be left hard after drawing or it can be heat treated (mainly annealed). This affects the resistivity and thus the wire’s resistance. In addition, the purity of copper varies and this can be deliberate depending on requirements for different applications, and the tiny amounts of impurity influence the resistivity also.
Finally, nowhere are we assured either wire has a uniform diameter over its length. All these factors have consequences for the answer yet we blithely ASSUME the details. Maybe this makes sense for a class assignment but in the real world assuming is a bad habit which gets people into trouble now and then. Another thing which makes sense is for students to do their own homework; the teacher or textbook author invents these exercises and grades them to improve the skills and understanding of the student to whom the task is assigned. Having some third, kind person do the thinking largely negates the intended benefits.
A copper wire has a resistance of 2.0Ω. A second copper wire is twice as long as the first wire, and its diameter is twice the diameter of the first wire. What is the resistance of the second wire?
If the resistance of a certain copper wire is 1 ohm, then what will the resistance of a similar nichrome wire be?
Two metallic wires made from copper have same length, but radius of wire 1 is half of that of other. The resistance of wire one is R. If both wires are joined together in series, what does the total resistance become?
A piece of wire has a resistance of 0.5 ohms. The length is doubled, and the area is increased four times. What is its resistance?
What is the ratio of resistance of two wires having the same length, but the diameter of the first wire is just double that of the second wire?
The resistance of a wire will be proportional to its length and inversely proportional to its area. See ()
So
R = k l / A
where l = length, A = cross section area and k is a constant. If we double the length we must halve the cross-section area. Hence we have a wire with length 2 l and area 0.5 A. The resistance of this wire will be
R = k (2 l) / (0.5 A) = 4 k l / A
four times the original.
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