Question

A copper wire has a diameter of 0.25mm and resistivity of ohm-meter How much does the resistance change if the diameter is doubled​

Answer 1

Explanation:

Resistivity (ρ) = 1.6 × 10-8 Ω m

Resistance (R) = 10 Ω

Diameter (d) = 0.5 mm

d = 5 × 10⁻⁴ m

Hence, we will get radius

Radius (r) = 0.25 mm

r = 0.25 × 10⁻³ m

r = 2.5 × 10⁻⁴ m

We need to find the area of cross-section

A = πr2

A = (22/7)(2.5 × 10⁻⁴)2

A = (22/7)(6.25×10⁻⁸)

A = 1.964 × 10-7 m2