Questions on resistivity

Resistivity

1. A coil of constantan wire of length 2 m has an area of cross-section of

7 x 10^-7 m². If its resistivity is 49 x 10^-8 Ω m, find its resistance.

2. A coil of wire 4 m long has a resistance of 20 Ω. If its resistivity is

108 x 10^-8 Ω m, find its area of cross-section.

3. A 1.75 m length of tin wire with a diameter of 0.70 mm is found to have a resistance of 0.5 Ω Find the resistivity of tin.

4. A resistor of 2 Ω is to be made from manganin wire of resistivity

42 x 10^-8 Ω m having a diameter of 0.42 mm. What length is required?

5. Find the resistance of a wire 2.8 m long with a resistivity of 22 x 10^-8 Ω m and a diameter of 0.56 mm.
6. A wire has a resistance of 2 Ω Find the resistance of a wire of the same material which is three times as long, but with half the diameter.