Consider a straight lenght of copper wire of diameter d=2 mm and Lenght = 10 m. The resistivity of copper is p= 1.68x10^-8 ohms. If the current in the wire is 1.5 A, then what is the putential difference across it?

Respuesta :

Answer:

The potential difference across the wire is 0.08V.

Explanation:

The relationship between voltage [tex]V[/tex], resistance [tex]R[/tex], and current [tex]I[/tex] is

[tex]V=IR[/tex],

Now, the resistance [tex]R[/tex] can be expressed as

[tex]R = \rho \dfrac{L}{A},[/tex]

where [tex]\rho[/tex] is the resistivity, [tex]L[/tex] is the length, and [tex]A[/tex] is the cross sectional area of the wire.

The cross sectional area [tex]A[/tex] of 2mm diameter wire is

[tex]A = \pi (\dfrac{2*10^{-3}}{2} )^2[/tex]

[tex]A = \pi *10^{-6}m^2[/tex],

therefore, the resistance is

[tex]R = (1.68*10^{-8}) \dfrac{(10m)}{\pi *10^{-6}},[/tex]

[tex]R = 0.0535\: \Omega[/tex].

Now, we are told that the current through the wire is 1.5A; therefore the potential difference across it will be

[tex]V = IR = (1.5A)*(0.0535 \Omega)[/tex]

[tex]\boxed{V= 0.08\:volts }[/tex]

To conclude, the potential difference across the wire is 0.08V.