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Question
A 10 m long wire of a particular material is of resistance 5Ω What will be the resistance of 10m long wire of the same material but the double radius.
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Solution
Given: The resistance of 10 m long wire = 5 Ω
For the wire of double the radius, the area of cross-section (a = πr2) of wire will be four times that of previous wire. Since resistance R α `1/"a"`. So the resistance of new wire will be one-fourth of the previous wire i.e., it will be `1/4 xx 5 Omega = 1.25 Omega`
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