2) Determine the resistance at 20 degrees Celsius, of 25m of solid aluminum round wire having a radius of 2mm. (Recall the relationship R=pl/A. The resistivity for Aluminum at 20 degrees Celsius = 2.8 x 10-8 Ωm).

2. radius = 2 mm = 0.002 meters.

A = pi*r^2 = 3.14 * (2*10^-3)^2 = 1.26*10^-5 m^2.

R = p*L/A = 2.8*10^-8 * 25/1.26*10^-5 = 0.056 Ohms.

To determine the resistance of the solid aluminum round wire at 20 degrees Celsius, you can use the formula R = ρL/A, where R is the resistance, ρ is the resistivity of aluminum, L is the length of the wire, and A is the cross-sectional area of the wire.

Given information:
- Resistivity of Aluminum at 20 degrees Celsius (ρ) = 2.8 x 10^-8 Ωm
- Length of the wire (L) = 25m
- Radius of the wire (r) = 2mm

Before we can calculate the resistance, we need to find the cross-sectional area (A) of the wire. The formula for the cross-sectional area of a circle is A = πr^2, where r is the radius.

Converting the radius from millimeters to meters:
- Radius (r) = 2mm = 2 x 10^-3 m

Now we can calculate the cross-sectional area:
- A = π(2 x 10^-3)^2
- A = π(4 x 10^-6)
- A = 4π x 10^-6 m^2 (approximated)

Now we have all the required values to calculate the resistance:
- R = ρL/A
- R = (2.8 x 10^-8 Ωm)(25m)/(4π x 10^-6 m^2)
- R = (2.8 x 10^-8 Ωm)(25m)/(4 x 3.14 x 10^-6 m^2)
- R ≈ 5.64 x 10^-4 Ω (approximated)

Therefore, the resistance of the 25m long solid aluminum round wire with a radius of 2mm at 20 degrees Celsius is approximately 5.64 x 10^-4 Ω.