# Tunnelling a Rectangular Barrier

Electricity and Magnetism Level 5

Let there be a rectangular barrier of potential $$+2eV$$ in the region $$0<x<L$$. If the kinetic energy of an electron is equal to $$+1eV$$, how wide must the barrier be so that the transmission probability is $${10}^{-3}$$. Give your answers in units of Angstroms.

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