A copper wire is 2.0 mm thick and 2 meters long. What is the resistance?
To calculate the resistance of a copper wire, we can use the resistivity formula: R is resistance (unit: ohms, Ω) ρ is the resistivity of the material (unit: ohms · meters, Ω·m) L is the length of the wire (unit: m, m) A is the cross-sectional area of the wire (unit: square meters, m²)For copper wires, the resistivity is approximately 1.72×10−8Ω⋅m (the standard value at 20°C).First, we need to calculate the cross-sectional area A of the wire. Suppose the wire has a circular cross-section and a d