Q. 154.1( 16 Votes )
A copper wire has
(a) From the given information,
Radius of wire, r =
Then area of cross-section will be,
Resistance, R= 10
And, Length, L = (To be calculated)
Now, putting these values in the formula:
Thus, the length of copper wire required to make 10 resistance will be 122.5 meters.
(b) The resistance of a wire is inversely proportional to the square of its diameter. So, when the diameter of the wire is doubled (that is, made 2 times), then its resistance will become (one-fourth).
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