Question

calculate the resistance of 1km long copper wire of radius 1mm (resistivity of copper is 1.72×10^-8 ohm metre

Answer 1

Solution :

Length of copper wire(l) = 1 km = 1000 m
Radius of the copper wire(r) = 1 mm = 1 x 10^-3 m
Resistivity of the copper (p) = 1.72 x 1 0-8 W m

Area of cross section = pi * r^2 = 3.14 x 10^-3

Answer 2

GIVEN THAT

• Length of copper wire = 1 km = 1000 m
• Radius of copper wire = 1 mm = 1 × 10-³ m
• Resistivity of copper = 1.72 x 10⁻⁸

CALCULATION OF RESISTANCE

• (Resistivity of copper × Length)/(Area)
• (Resistivity of copper × Length)/(πr²)
• [1.72×10⁻⁸*1000]/[22/7×(1×10⁻³)²]
• 5.5 ohm