# Homework 13 Question 8

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An electron is in the ground state of an infinite square well. The energy of the ground state is E1 = 1.14 eV.

(a) What wavelength of electromagnetic radiation would be needed to excite the electron to the n = 2 state?

(b) What is the width of the square well?

I am so confused by this question. I have been using the equation E = (n^2 h^2)/ (8mL^2) and solving the equation for L. Am I using n=1 or n=2? Is the value I get for L my final answer or do I need to plug it into another equation?

The equation is correct. For n=1, it is the ground state, which is $E_1=\frac {h^2}{8mL^2}$. For n>1 states, the energy can be written as $E_n=n^2E_1$. This will allow you to find the difference between states easily.
(b)To find L, one can use any value of n. For simplicity, $E_1$ can be used to find L.