Question

You are putting the electrical wiring in your new house, and you are considering using aluminum wiring, which is cheap and a good conductor. However, you also know that aluminum tends to form an oxide surface layer (Al2O3) which can be as much as several nanometers thick. This layer could cause a problem in making electrical contacts with outlets, for ex- ample, since it presents a barrier of roughly 10 eV to the flow of electrons in and out of the Aluminum. Your requirement is that the probability of transmission across any contact must be T > 10^−10, or else the resistance will be too high for the high current you are using, causing a fire risk. Do you decide to use aluminum wiring or not? For this problem, use the more approximate form of the tunneling formula, T ≈ exp(−2κL).

Answer 1

approximate tunneling formula is

E = 110 eV, V = 10eV and let L = 4nm

Then,

​

thus transmission is

Since, transmission is very small, aluminium wiring should not be used.