The electric resistance of a particular wire of iron is R. If its length and radius are doubled, then:
 

Resistances \(n\), each of \(r\) ohm, when connected in parallel give an equivalent resistance of \(R\) ohm. If these resistances were connected in series, the combination would have resistance in ohms, equal to:
1. \(\dfrac{R}{n^2}\)
2. \(\dfrac{R}{n}\)
3. \(nR\)
4. \(n^2R\)

When a wire of uniform cross-section a, length l, and resistance R is bent into a complete circle, the resistance between any two diametrically opposite points will be:

1. R/2

2. R/4

3. R/8

4. 4R