Given l=1m d=0.3mm A=πr²=3.14*2.25*10^-8 =7.065*10^-8m²Now, P=R x A/l =26 x 7.065 x 10^-8 =183.69 x 10^-8 ohm mThus, the resistivity of the metal wire at 20degree C is 183.69 x 10^-8 ohm m

Given:
- Length of the metal wire (L) = 1m
- Resistance of the wire (R) = 26 ohm
- Diameter of the wire (d) = 0.3mm

To Find:
- Resistivity of the metal wire at 20 degrees Celsius

Formula:
The resistance of a wire is given by 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

The cross-sectional area (A) of a wire can be calculated using the formula:

A = π * (d/2)^2

Where:
- d is the diameter of the wire

Solution:

Step 1: Convert the diameter to meters
- Given diameter of the wire (d) = 0.3mm
- Convert mm to meters by dividing by 1000
- d = 0.3mm / 1000 = 0.0003m

Step 2: Calculate the cross-sectional area (A)
- Given diameter of the wire (d) = 0.0003m
- Calculate the radius (r) by dividing the diameter by 2
- r = 0.0003m / 2 = 0.00015m
- Calculate the cross-sectional area (A) using the formula
- A = π * (0.00015m)^2

Step 3: Calculate the resistivity (ρ)
- Given resistance of the wire (R) = 26 ohm
- Given length of the wire (L) = 1m
- Rearrange the formula R = (ρ * L) / A to solve for resistivity ρ
- ρ = (R * A) / L

Step 4: Substitute the values into the formula and calculate the resistivity (ρ)
- R = 26 ohm
- A = π * (0.00015m)^2 (calculated in Step 2)
- L = 1m
- ρ = (26 ohm * A) / L

Step 5: Evaluate the expression to find the resistivity (ρ)
- Substitute the values into the formula and calculate the resistivity
- ρ = (26 ohm * A) / L

Step 6: Convert the answer to scientific notation if required
- The resistivity of the metal wire at 20 degrees Celsius is the final answer.

Conclusion:
The resistivity of the metal wire at 20 degrees Celsius is the calculated value of ρ, obtained through the above steps.