2. when a potential difference of 12 v is applied to a wire 6.9 m long and 0.33 mm in diameter
the result is an electric current of 2.1 a. what is the resistivity of the wire?

Apply Ohm's law:

V = IR

V = potential difference, I = current, R = resistance

Resistance of a wire:

R = ρL/A

ρ = resistivity, L = length, A = cross-sectional area

Area of wire's cross-sectional area:

A = π(d/2)²

A = area, d = diameter

Substitute R:

V = IρL/A

Substitute A:

V = IρL/(π(d/2)²)

Given values:

V = 12V, I = 2.1A, L = 6.9m, d = 0.33×10⁻³m

Plug in these values and solve for ρ:

12 = 2.1ρ(6.9)/(π(0.33×10⁻³/2)²)

ρ = 7.1×10⁻⁸Ω·m

ill do it for 100, also this isnt 80 its 40

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