High School

6- A copper wire of length L=20 m long and radius r=0.001 m with resistivity rho=1.69×10^−8 Ω.m given. See the figure a. Calculate the resistance R

b. Calculate the conductivity σ

c. If the current of I=2.5Amp flows through this wire, calculate the Electric field?

Answer :

Final answer:

The resistance of the copper wire is 0.107 Ω. The conductivity of the copper wire is 5.92×10^7 Ω^−1.m^−1. The electric field cannot be calculated without knowing the voltage across the wire.

Explanation:

To calculate the resistance (R) of the copper wire, we can use the formula:

R = (ρ * L) / A

Given:

  • Length of the wire (L) = 20 m
  • Radius of the wire (r) = 0.001 m
  • Resistivity of copper (ρ) = 1.69×10^−8 Ω.m

First, we need to calculate the cross-sectional area (A) of the wire using the formula:

A = π * r^2

Substituting the given values:

A = π * (0.001)^2 = 3.14×10^−6 m^2

Now, we can substitute the values of ρ, L, and A into the formula for resistance:

R = (1.69×10^−8 * 20) / (3.14×10^−6) = 0.107 Ω

Therefore, the resistance of the copper wire is 0.107 Ω.

To calculate the conductivity (σ) of the copper wire, we can use the formula:

σ = 1 / ρ

Substituting the value of ρ:

σ = 1 / (1.69×10^−8) = 5.92×10^7 Ω^−1.m^−1

Therefore, the conductivity of the copper wire is 5.92×10^7 Ω^−1.m^−1.

To calculate the electric field (E) when a current of 2.5 Amp flows through the wire, we need to know the voltage (V) across the wire. However, the voltage is not given in the question, so we cannot calculate the electric field without this information.

Learn more about calculating resistance, conductivity, and electric field in a copper wire here:

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