What is the resistance of a 3.9-m length of copper wire 1.1 mm in diameter? The resistivity of copper is 1.68×10^−8Ω⋅m.

R=______ Ω

Please Help. I've been at this for hours.

Hours? Ridiculous.

resistance=resitivity*length/area

area= PI (d/2)^2 you are given diameter d, 0.0011meter

area= PI (.00055)^2=9.50e-7

can you handle it from here?

To calculate the resistance of a wire, you can use the formula:

R = (ρ * L) / A

Where:
- R is the resistance of the wire
- ρ (rho) is the resistivity of the material
- L is the length of the wire
- A is the cross-sectional area of the wire

In this case, the resistivity of copper (ρ) is given as 1.68×10^−8 Ω⋅m. The length of the wire (L) is given as 3.9 m. To calculate the cross-sectional area (A) of the wire, we need to find the radius of the wire first.

The diameter of the wire is given as 1.1 mm. To find the radius, divide the diameter by 2:

Radius (r) = Diameter / 2 = 1.1 mm / 2 = 0.55 mm = 0.55×10^−3 m

Now, we can calculate the cross-sectional area (A) of the wire using the formula for the area of a circle:

A = π * r^2

Substituting the value of the radius:

A = π * (0.55×10^−3 m)^2

Finally, substitute the values of ρ, L, and A into the resistance formula and solve for R:

R = (1.68×10^−8 Ω⋅m * 3.9 m) / (π * (0.55×10^−3 m)^2)

Evaluating the expression will give you the resistance (R) of the copper wire.