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The Heisenberg uncertainty principle can be expressed in the form $$ \Delta E \cdot \Delta t \geqq \frac{h}{4 \pi} $$ where \(E\) represents energy and \(t\) represents time. Show that the units for this form are the same as the units for the form used in this chapter: $$ \Delta x \cdot \Delta(m v) \geq \frac{h}{4 \pi} $$

Short Answer

Expert verified
In both forms of the Heisenberg uncertainty principle, the units are the same: Joule-seconds (Js). For the first form \(\Delta E \cdot \Delta t = J \cdot s\), and for the second form \(\Delta x \cdot \Delta(mv) = J \cdot s\). Also, the units of the Planck constant (\(h\)) term are \(J \cdot s\). Thus, both forms have equivalent units, validating the Heisenberg uncertainty principle for both expressions.

Step by step solution

01

Units of Terms in the First Form

For the first form, we need to find the units of \(\Delta E \cdot \Delta t\). The units of energy (\(E\)) are Joules (J) and the units of time (\(t\)) are seconds (s). So, \(\Delta E \cdot \Delta t = J \cdot s\) Now let's find the units of the terms in the second form.
02

Units of Terms in the Second Form

For the second form, we need to find the units of \(\Delta x \cdot \Delta(mv)\). The position \(x\) has units of meters (m), and the product of mass (\(m\)) and velocity (\(v\)) has units of kg m/s. Therefore, \(\Delta x \cdot \Delta(mv) = m \cdot (kg \cdot m/s) = J \cdot s\)
03

Units of the Constant `h`

The constant `h` is the Planck constant, and it has units of Joule-seconds (Js). The term \(\frac{h}{4\pi}\) in both forms has units of \(J\cdot s\): \(\frac{h}{4\pi} = \frac{Js}{4\pi}\)
04

Comparing the Units

Now, we compare the units of both forms: 1. First form: \(\Delta E \cdot \Delta t \geqq \frac{h}{4 \pi}\) has units of \(J \cdot s \geqq J\cdot s\) 2. Second form: \(\Delta x \cdot \Delta(m v) \geq \frac{h}{4 \pi}\) has units of \(J \cdot s \geq J\cdot s\) Since the units of both forms are the same, the Heisenberg uncertainty principle holds true for both formulations.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Quantum Mechanics
At the heart of the most perplexing phenomena in the universe lies the field of quantum mechanics, a cornerstone of modern physics.

Quantum mechanics delves into the behavior and interactions of subatomic particles, such as electrons and photons, at the smallest scales imaginable. Unlike classical physics, which can predict the motion of planets and projectiles with great precision, quantum mechanics reveals a world where probabilities and uncertainties dominate.

  • In this realm, particles can exist in multiple states simultaneously, known as superposition.
  • They can affect each other instantly over vast distances—a phenomenon called entanglement.
  • Observing a particle can fundamentally alter its state, a concept splashed into the mainstream with Schrödinger's cat thought experiment.
These quantum behaviors often seem counterintuitive because they do not align with our everyday experiences. It's these principles that inform the Heisenberg uncertainty principle, which sets fundamental limits on the precision with which certain pairs of physical properties, like position and momentum, can be known simultaneously.
Planck Constant
The Planck constant, symbolized as `h`, is of paramount importance in quantum mechanics, holding the universe's smallest actions in its dimensional grip.

It was Max Planck who introduced this constant in 1900, proposing that energy is quantized, meaning it could be released or absorbed only in discrete amounts or 'quanta'. This constant is central to the quantum theory and is a key element in several fundamental equations, including the energy of a photon `E = hν`, where `ν` is the frequency of the photon.

  • The value of the Planck constant is approximately 6.62607015 × 10^-34 joule-seconds (Js).
  • In addition to connecting energy and frequency, `h` also relates to the wavelength of particles via the de Broglie equation `λ = h/p`, with `λ` being the wavelength and `p` the momentum.
Understanding the Planck constant is crucial when dealing with the Heisenberg uncertainty principle, as it sets the scale for the 'quantum of action' that underlies the inherent limitations on the precision of measurements at quantum levels.
Dimensional Analysis
Dimensional analysis is a mathematical tool often used in physics to check the consistency of equations, convert units, or to derive relationships between physical quantities.

It's based on the principle that you can only equate or compare quantities if they have the same dimensions. For instance, adding length to time directly would be like adding apples and oranges – it’s nonsensical from a dimensional perspective.

  • One common use is to ensure that the units on both sides of an equation match, affirming that an equation is dimensionally consistent.
  • Another application helps in estimating the results of complex calculations just by analyzing the units and dimensions involved.
The solution to the Heisenberg uncertainty principle exercise employs dimensional analysis to verify that both forms of the principle have units that are consistent, thereby showing that they are dimensionally equivalent. The comparison of units, Joule-seconds on both sides, confirms the validity of the expressions. This clear and simple method is a powerful test of physical equations and principles like Heisenberg's, ensuring their dimensional integrity.

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Most popular questions from this chapter

In the ground state of mercury, Hg, a. how many electrons occupy atomic orbitals with \(n=3 ?\) b. how many electrons occupy \(d\) atomic orbitals? c. how many electrons occupy \(p_{z}\) atomic orbitals? d. how many electrons have spin "up" \(\left(m_{s}=+\frac{1}{2}\right) ?\)

The first ionization energies of As and Se are 0.947 and \(0.941 \mathrm{MJ} / \mathrm{mol},\) respectively. Rationalize these values in terms of electron configurations.

A carbon-oxygen double bond in a certain organic molecule absorbs radiation that has a frequency of \(6.0 \times 10^{13} \mathrm{s}^{-1}\). a. What is the wavelength of this radiation? b. To what region of the spectrum does this radiation belong? c. What is the energy of this radiation per photon? d. A carbon-oxygen bond in a different molecule absorbs radiation with frequency equal to \(5.4 \times 10^{13} \mathrm{s}^{-1} .\) Is this radiation more or less energetic?

Calculate the wavelength of light emitted when each of the following transitions occur in the hydrogen atom. What type of electromagnetic radiation is emitted in each transition? a. \(n=3 \rightarrow n=2\) b. \(n=4 \rightarrow n=2\) c. \(n=2 \rightarrow n=1\)

As the weapons officer aboard the Starship Chemistry, it is your duty to configure a photon torpedo to remove an electron from the outer hull of an enemy vessel. You know that the work function (the binding energy of the electron) of the hull of the enemy ship is \(7.52 \times 10^{-19} \mathrm{J}\) a. What wavelength does your photon torpedo need to be to eject an electron? b. You find an extra photon torpedo with a wavelength of \(259 \mathrm{nm}\) and fire it at the enemy vessel. Does this photon torpedo do any damage to the ship (does it eject an electron)? c. If the hull of the enemy vessel is made of the element with an electron configuration of \([\mathrm{Ar}] 4 s^{1} 3 d^{10},\) what metal is this?

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