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## Homework Statement

A 10eV electron is incident on a potential barrier of height 25eV and width 1nm. Estimate (order of magnitude) the probability that the electron will tunnel through the barrier, repeat your calculations for a barrier of 01.nm

## Homework Equations

T=16(E/V)(1-(E/V))exp(-2[tex]\alpha[/tex]a)

[tex]\alpha[/tex]=[tex]\sqrt{}(2m(V-E))[/tex]/[tex]\hbar[/tex]

## The Attempt at a Solution

E=10eV=1.6x10^-18J, V=25eV=4x10^-18J

[tex]\alpha[/tex]=[tex]\sqrt{}(2*9.1x10^-31(4x10^-18-1.6x10^-18))[/tex]/6.62x10^-34=3.157x10^9

T=3.84exp(-2*3.157x10^9*1x10^-9)=7x10^-3???

the answer is meant to be 9.2x10^-9 or 4.95x10^-13???? sorry, my book says 4.95 and the lecturers notes say 9.2... doesnt matter, coz im way way off...

please can someone help me where i am going wrong?