Modern Physics

Particle in a Box Energy Levels

En=n2h28mL2E_n = \frac{n^2 h^2}{8mL^2}

Quantized energy levels for a particle confined to a one-dimensional infinite potential well.

Variables

En
Energy of level n
J
n
Quantum number (n = 1, 2, 3...)
Allowed values: greater than 0, whole number
unitless
h
Planck constant
Allowed values: greater than 0
J·s
m
Particle mass
Allowed values: greater than 0
kg
L
Box length
Allowed values: greater than 0
m

Derivation

Solved from Schrödinger equation with boundary conditions ψ(0) = ψ(L) = 0.

Your notes

0/5000

Constants in this formula

h
6.626 070 15 × 10⁻³⁴. Exact by definition.
J·s

Check value

Round inputs run through this page's calculator, with each constant at its tabulated value. Use it to test your own working or a rearranged form. It is a test case, not a real-world example.

  • n = 2 (Quantum number (n = 1, 2, 3...))
  • h = 6.626 070 15 × 10⁻³⁴ J·s (Planck constant)
  • m = 3 kg (Particle mass)
  • L = 4 m (Box length)

Result: En = 4.573417 × 10⁻⁶⁹ J

Other modern physics formulas with the same quantities

Where this formula is listed

Common questions

What is the Particle in a Box Energy Levels formula?

Particle in a Box Energy Levels is written E_n = n²h²/(8mL²). Quantized energy levels for a particle confined to a one-dimensional infinite potential well. It belongs to Modern Physics, under Quantum Mechanics.

What are the units in E_n = n²h²/(8mL²)?

In SI units, E_n is energy of level n, measured in J; n is quantum number (n = 1, 2, 3...) (dimensionless); h is planck constant, measured in J·s; m is particle mass, measured in kg; L is box length, measured in m.

How is the Particle in a Box Energy Levels formula derived?

Solved from Schrödinger equation with boundary conditions ψ(0) = ψ(L) = 0. The result is E_n = n²h²/(8mL²).