An electron traveling at 2.4×105 m/s has an uncertainty in its velocity of 1.01×105 m/s .

You may want to reference (Page) Section 7.4 while completing this problem.

Part A
What is the uncertainty in its position?

Respuesta :

Answer:

Approximately at least [tex]5.73\times 10^{-10}\; \rm m[/tex].

Explanation:

Look up the following values:

  • Electron rest mass: approximately  [tex]9.109 \times 10^{-31}\; \rm kg[/tex].
  • Planck's constant: approximately [tex]6.626 \times 10^{-34}\; \rm kg \cdot m^2 \cdot s^{-1}[/tex].

The uncertainty in the electron's velocity is [tex]\Delta v = 1.01 \times 10^{5}\; \rm m \cdot s^{-1}[/tex]. Momentum is equal to mass times velocity. Hence, the uncertainty in the electron's momentum would be

[tex]\begin{aligned}\Delta p &= m \cdot \Delta v \\ &\approx 9.109 \times 10^{-31} \;\rm kg \times 1.01 \times 10^5\; \rm m \cdot s^{-1} \\ &\approx 9.20 \times 10^{-26}\; \rm kg \cdot m \cdot s^{-1}\end{aligned}[/tex].

By Heisenberg's Uncertainty Principle, the product of uncertainty in an object's momentum [tex]\Delta p[/tex] and uncertainty in its position [tex]\Delta x[/tex] is at least [tex]\displaystyle \frac{h}{4\, \pi}[/tex].

That is:

[tex]\displaystyle \Delta p \cdot \Delta x \ge \frac{h}{4\, \pi}[/tex].

Rearrange to obtain:

[tex]\begin{aligned} \Delta x \ge \frac{h}{4\, \pi\, \Delta p} &\approx\frac{6.626\times 10^{-34}\; \rm kg \cdot m^2 \cdot s^{-1}}{(4\,\pi)\times 9.20\times 10^{-26}\; \rm kg \cdot m \cdot s^{-1}} \approx 5.73 \times 10^{-10}\; \rm m\end{aligned}[/tex].

In other words, the uncertainty in this electron's position is at least [tex]5.73\times 10^{-10}\; \rm m[/tex].