The resistance of a metal wire of length 1 m is 50 Ω at 30°C. Suppose the diameter of the wire is 0.3 mm. Now another wire has the same material and the same length (at 30°C), but the diameter is increased to 0.6 mm. The resistance of the new wire is:
1
20.5 Ω
2
2.5 Ω
3
120.5 Ω
4
12.5 Ω