Question
A copper wire has radius $0.800 \mathrm{~mm}$ and carries current $I$ at $20.0^{\circ} \mathrm{C} .$ A silver wire with radius $0.500 \mathrm{~mm}$ carries the same current and is also at $20.0^{\circ} \mathrm{C}$. Let $E_{\mathrm{Cu}}$ be the electric field in the copper wire and $E_{\mathrm{Ag}}$ be the electric field in the silver wire. What is the ratio $E_{\mathrm{Cu}} / E_{\mathrm{Ag}} ?$
Step 1
e., $J = \frac{I}{A}$. It is also given by the ratio of the electric field $E$ across the ends of the conductor to its resistivity $\rho$, i.e., $J = \frac{E}{\rho}$. Show more…
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A copper wire has a radius of 0.800 mm and carries a current I at 20.0°C. A silver wire with a radius of 0.500 mm carries the same current and is also at 20.0°C. Let ECu be the electric field in the copper wire and EAg be the electric field in the silver wire. What is the ratio ECu/EAg?
A silver wire has resistivity $\rho=1.62 \times 10^{-3} \mathrm{R} \cdot \mathrm{m}$ and a crosssectional area of $5.00 \mathrm{~mm}^{2}$. The current in the wire is uniform and changing at the rate of 2000 A/s when the current is $54.0 \mathrm{~A}$. (a) What is the magnitude of the (uniform) electric field in the wire when the current in the wire is $100 \mathrm{~A}$ ? (b) What is the displacement current in the wire at that time? (c) What is the ratio of the magnitude of the magnetic field due to the displacement current to that due to the current at a distance $r$ from the wire?
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