David Sang and Graham Jones Solutions for Chapter: Electric Current, Potential Difference and Resistance, Exercise 5: Questions

Calculate the current in a gold wire of crosssectional area $2.0{ \mathrm{mm}}^2$ when the mean drift velocity of the electrons in the wire is $0.10 \mathrm{mm}{ \mathrm{s}}^{-1}$. The electron number density for gold is $5.9\times {10}^{28}{ \mathrm{m}}^{-3}$.

Calculate the mean drift velocity of electrons in a copper wire of diameter $1.0 \mathrm{mm}$ with a current of $5.0 \mathrm{A}$. The electron number density for copper is $8.5\times {10}^{28}{ \mathrm{m}}^{-3}$.

A length of copper wire is joined in series to a length of silver wire of the same diameter. Both wires have a current in them when connected to a battery. Explain how the mean drift velocity of the electrons will change as they travel from the copper into the silver. Electron number densities:

Copper $\mathrm{n}=8.5\times {10}^{28}{ \mathrm{m}}^{-3}$

Silver $\mathrm{n}=5.9\times {10}^{28}{ \mathrm{m}}^{-3}$.