Question

A wire of length 5 m and radius I mm has a resistance of l ohm. What length of the wire of the same
material at the same temperature and of radius 2 mm will also have a resistance of l ohm
(a) 125 m
(b) 2.5 m
(c) 10 m
d) 20 m
​

Answer 1

the length of a wire is proportional to its lenght

5×1=2×x

x=2.5 ans.