For a particle in a box, in one spatial dimension and of length L, confined to the region 0 < x < L , the energy eigenstates are Ψ Ψ n = 2 L sin ⁡ ⁡ ( n π π L x ) and zero elsewhere. The associated probability currents are j n = i ℏ ℏ 2 m ( Ψ Ψ n ∗ ∗ ∂ ∂ Ψ Ψ n ∂ ∂ x − − Ψ Ψ n ∂ ∂ Ψ Ψ n ∗ ∗ ∂ ∂ x ) = 0 since Ψ Ψ n = Ψ Ψ n ∗ ∗