A copper wire has radius r = 0.0205 cm, is 2.95 m long, has resistivity ρ = 1.72 · 10−8 Ω m, and carries a c?
A copper wire has radius r = 0.0205 cm, is 2.95 m long, has resistivity
ρ = 1.72 · 10−8 Ω m,
and carries a current of 0.370 A. The wire has density of charge carriers of 8.50 · 1028 electrons/m3. (When entering units, use ohm for Ω.)
(b) What is the electric potential difference, ΔV, across the wire?
(c) What is the electric field, E, in the wire? (Enter the magnitude of the electric field.)
- u.n. oLv 59 years agoFavorite Answer
(a) and (b) - same as UV.
(c): j = sigma*E, j = current density and E = electric field, sigma - conductivity
sigma = 1/resistivity = A/(L*resistivity), L = length
But R = (resistivity)*L/A
So sigma = L/AR
j = i/A i = current
So E = j/sigma = iR/L
PS UV: You meant rho, not R in your answer.
- QuarkLv 69 years ago
(a) Resistance of the wire :
R = ρ * L/A
= 1.72 x 10^-8 * 2.95/(π * (2.05 x 10^-4)^2)
= 0.384 Ω
(b) ΔV =I * R
= 0.370 * 0.384 = 0.142 volts
(c) J = I/A = σ * E
--> E = I/A * σ --> σ = 1/R
--> E = I * R/A