Question

original length. Calculate the resistance or

13. A copper wire has diameter 0.5 mm and resistivity 1.62 x 10 ohm-m. What will be the length
of this wire to its resistance 10 ohm? How much does the resistance change if the diameter is doubled​

Answer 1

Given,

diameter of copper wire = 0.5mm = 5 × 10-⁴ m

resistivity = 1.6 × 10^-8 ohm.m

resistance = 10 ohm

Length = ?

we know,

R = dL/A

where R , d , L and A are resistance , resistivity , length and cross section area.

10 = 1.6 × 10^-8 × L/(πr²)

L = 10 × 3.14 × (2.5 × 10^-4)² × 10^8/1.6

L = 10× 3.14 × 6.25/1.6

L = 122.656 m