The graph in FIGURE EX40.15 shows the potential-energy function U(x) of a particle. Solution of the Schrödinger equation finds that the n = 3 level has E3 = 0.5 eV and that the n = 6 level has E6 = 2.0 eV. Redraw this figure and add to it the energy lines for the n = 3 and n = 6 states.
Ch 40: One-Dimensional Quantum Mechanics
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 40, Problem 17a
INT An electron is confined in a harmonic potential well that has a spring constant of 2.0 N/m. What are the first three energy levels of the electron?
Verified step by step guidance1
Step 1: Recognize that the problem involves a quantum harmonic oscillator. The energy levels of a quantum harmonic oscillator are given by the formula: , where is the quantum number (starting from 0), is the reduced Planck's constant, and is the angular frequency of the oscillator.
Step 2: Calculate the angular frequency using the formula , where is the spring constant (2.0 N/m) and is the mass of the electron (approximately kg).
Step 3: Substitute the calculated value of into the energy formula for the quantum harmonic oscillator. For the first three energy levels, use , , and .
Step 4: For each energy level, calculate the corresponding energy using the formula . Remember that (reduced Planck's constant) is approximately J·s.
Step 5: Express the first three energy levels in terms of their values (symbolically or numerically, depending on the calculation). Ensure the units are consistent throughout the calculation, and verify the results for accuracy.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Quantum Harmonic Oscillator
The quantum harmonic oscillator is a fundamental model in quantum mechanics that describes a particle subject to a restoring force proportional to its displacement from an equilibrium position. This model is crucial for understanding systems like electrons in potential wells, where the energy levels are quantized and can be calculated using specific formulas.
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Energy Levels
In quantum mechanics, energy levels refer to the discrete values of energy that a quantum system, such as an electron in a harmonic potential well, can occupy. For a harmonic oscillator, these energy levels are given by the formula E_n = (n + 1/2)ħω, where n is a non-negative integer, ħ is the reduced Planck's constant, and ω is the angular frequency of the oscillator.
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Spring Constant and Angular Frequency
The spring constant (k) is a measure of the stiffness of a spring, and it plays a vital role in determining the angular frequency (ω) of a harmonic oscillator, given by ω = √(k/m), where m is the mass of the particle. In this context, knowing the spring constant allows us to calculate the angular frequency, which is essential for determining the energy levels of the electron in the harmonic potential well.
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Related Practice
Textbook Question
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Textbook Question
Sketch the n = 8 wave function for the potential energy shown in FIGURE EX40.13.
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INT An electron is confined in a harmonic potential well that has a spring constant of 2.0 N/m. What wavelength photon is emitted if the electron undergoes a 3→1 quantum jump?
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Use the data from Figure 40.24 to calculate the first three vibrational energy levels of a C=O carbon-oxygen double bond.
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INT An electron is confined in a harmonic potential well that has a spring constant of 12.0 N/m. What is the longest wavelength of light that the electron can absorb?
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A helium atom is in a finite potential well. The atom’s energy is 1.0 eV below U₀. What is the atom’s penetration distance into the classically forbidden region?
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