Answer:
the resistance of the copper wire 20 meters long and with a diameter of 0.05 cm is 0.342 ohms.
Step-by-step explanation:
To calculate the resistance of the copper wire, we need to use the formula:
R = (ρ * L) / A
where R is the resistance of the wire, ρ is the resistivity of copper, L is the length of the wire, and A is the cross-sectional area of the wire.
The resistivity of copper is 1.68 × 10^-8 Ω·m.
First, we need to calculate the cross-sectional area of the wire:
A = π * (d/2)^2
A = π * (0.05cm/2)^2
A = 0.0019635 cm^2
Note that we converted the diameter from centimeters to meters, since the resistivity is given in ohms per meter.
Now, we can calculate the resistance of the wire:
R = (ρ * L) / A
R = (1.68 × 10^-8 Ω·m * 20m) / 0.0019635 cm^2
R = 0.342 Ω
Therefore, the resistance of the copper wire 20 meters long and with a diameter of 0.05 cm is 0.342 ohms.