If a particle conned to move in one dimension has wavefunction ψ(x), then the probability of nding it between any two points x1 and x2 is: P(x1, x2) = ˆx2 x1 dx |ψ(x)| 2 Calculate the probability of nding a particle between x1 = 0 and x2 = a/3 for the ground-state of a one-dimensional rigid box of size a. [Hint: the calculation involves an integral of the function sin2 θ. Use the identity 2 sin2 θ = 1 − cos 2θ.]

Respuesta :

Answer:

[tex]P(0,a/3)=\frac{1}{3}-\frac{\sqrt{3}}{4\pi}[/tex]

Step-by-step explanation:

The probability of finding a particle between two points is given by:

[tex]P(x_1,x_2)=\int_{x_1}^{x_2}|\Phi_n|^2dx[/tex]

Furthermore, the wave function of a nth state is given by:

[tex]\Phi_n=\sqrt{\frac{2}{a}}sin(\frac{n\pi x}{a})[/tex]

By replacing we obtain

[tex]P(0,\frac{x}{3})=\int_{0}^{\frac{a}{3}}\frac{2}{a}sin^2(\frac{n\pi x}{a})dx[/tex]

and by using the relation,

[tex]sin^2\theta=\frac{1}{2}(1-cos(2\theta))[/tex]

we get for the ground state (n=1):

[tex]P(0,a/3)=(\frac{2}{a})(\frac{1}{2})\int_{0}^{\frac{a}{3}}(1-cos(\frac{2\pi x}{a}))dx\\\\P(0,a/3)=(\frac{2}{a})(\frac{1}{2})[\frac{a}{3}-(\frac{a}{2\pi})sin(\frac{2\pi (a/3)}{a})]\\\\P(0,a/3)=(\frac{1}{a})[\frac{a}{3}-(\frac{a}{2\pi})(\frac{\sqrt{3}}{2})]=\frac{1}{3}-\frac{\sqrt{3}}{4\pi}[/tex]

hope this helps!!