/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 48 How fast does a proton have to b... [FREE SOLUTION] | 91Ó°ÊÓ

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How fast does a proton have to be moving in order to have the same de Broglie wavelength as an electron that is moving with a speed of \(4.50 \times 10^{6} \mathrm{m} / \mathrm{s} ?\)

Short Answer

Expert verified
The proton must move at \(2.73 \times 10^3 \text{ m/s}\).

Step by step solution

01

Identify the Given Information

We are given the speed of the electron, which is \( v_e = 4.50 \times 10^6 \text{ m/s} \). We need to find the speed \( v_p \) of a proton that has the same de Broglie wavelength as this electron.
02

Understand the De Broglie Wavelength Formula

The formula for the de Broglie wavelength \( \lambda \) is given by \( \lambda = \frac{h}{mv} \), where \( h \) is Planck's constant \( 6.626 \times 10^{-34} \text{ Js} \), \( m \) is the mass of the particle, and \( v \) is its velocity. The mass of an electron \( m_e \) is \( 9.109 \times 10^{-31} \text{ kg} \), and the mass of a proton \( m_p \) is \( 1.673 \times 10^{-27} \text{ kg} \).
03

Calculate the Electron's Wavelength

Using the de Broglie formula, compute the wavelength of the electron: \[ \lambda_e = \frac{h}{m_e v_e} = \frac{6.626 \times 10^{-34} \text{ Js}}{9.109 \times 10^{-31} \text{ kg} \times 4.50 \times 10^6 \text{ m/s}} = 1.62 \times 10^{-10} \text{ m} \].
04

Equate the Proton and Electron Wavelengths

Since the wavelengths are equal, we have \( \lambda_p = \lambda_e = 1.62 \times 10^{-10} \text{ m} \) for the proton. Substitute this into the de Broglie equation for the proton: \[ \lambda_p = \frac{h}{m_p v_p} \].
05

Solve for Proton's Speed

Rearrange the equation to solve for \( v_p \): \[ v_p = \frac{h}{m_p \lambda_p} = \frac{6.626 \times 10^{-34} \text{ Js}}{1.673 \times 10^{-27} \text{ kg} \times 1.62 \times 10^{-10} \text{ m}} = 2.73 \times 10^3 \text{ m/s} \].

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Key Concepts

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

Proton Speed
In the realm of quantum mechanics, understanding proton speed is crucial when exploring concepts like the de Broglie wavelength. Protons are much heavier than electrons, which means they require different speeds to match similar quantum properties such as wavelength. The task of determining the speed of a proton that possesses the same de Broglie wavelength as an electron centers around equating their wavelengths and using known constants for calculation.

The de Broglie formula, \( \lambda = \frac{h}{mv} \), links a particle's wavelength to its mass and velocity. Here, "\( v_p \)" represents the speed of the proton needed to match the wavelength of a given electron. By manipulating this formula, we isolate \( v_p \), allowing us to solve for the speed that confers both particles with equal wavelengths. This involves rearranging the formula to \( v_p = \frac{h}{m_p \lambda} \), using the given Planck's constant and known proton mass.

When we consider the proton, its substantially larger mass compared to an electron significantly impacts the velocity value required to maintain equal wavelengths. As calculated, the speed for the proton is \( 2.73 \times 10^3 \text{ m/s} \). This calculation demonstrates the fascinating interplay between mass, velocity, and wavelength in quantum mechanics.
Electron Velocity
Electrons are intriguing due to their very high speeds even though they have significantly less mass than protons. In our exercise, the electron's velocity is given as \( 4.50 \times 10^6 \text{ m/s} \). This incredible speed is pivotal in determining properties such as the de Broglie wavelength. A particle's wavelength diminishes as its speed increases, highlighting the critical relationship between velocity and quantum properties.

The formula for de Broglie wavelength involves electron velocity, mass, and Planck's constant:
  • \( \lambda = \frac{h}{m v} \)
For the electron, the task is to calculate the resultant wavelength when traveling at the given speed. Substituting its mass \( m_e = 9.109 \times 10^{-31} \text{ kg} \) and its velocity into the equation gives us a specific wavelength value. The calculated electron de Broglie wavelength is \( 1.62 \times 10^{-10} \text{ m} \).

This value plays a critical role when determining the corresponding speed of heavier particles like protons for wavelength matching. It also sheds light on how tiny changes in mass and velocity can significantly impact a particle’s wave-like behavior.
Planck's Constant
Planck's constant, denoted as \( h \), is fundamental in quantum mechanics, setting the scale for quantum effects. It emerges frequently in formulas that describe the behavior of particles at atomic and subatomic levels. In our exercise, Planck's constant is equipped with a value of \( 6.626 \times 10^{-34} \text{ Js} \).

Planck's constant ties together the energy of photons with their frequency and influences the de Broglie wavelength formula:
  • \( \lambda = \frac{h}{mv} \)
This constant symbolizes the "quantum action" limit below which classical mechanics fails, prompting quantum phenomena to dominate. When calculating the de Broglie wavelength, \( h \) acts as a proportional factor relating the particle's speed and mass to its wave properties.

Understanding Planck’s constant is essential to grasping the abstract but crucial bridge between wave and particle nature, proving indispensable in applying quantum mechanics to real-world problems.
Particle Mass
Particle mass significantly impacts how particles exhibit wave-like properties. In the context of the de Broglie wavelength, the mass term acts as an inverse scaling factor, dramatically altering the necessary speeds to achieve equivalent wavelengths between particles of different masses.

For electrons and protons, the disparity in mass is a key component. The electron's mass is mere \( 9.109 \times 10^{-31} \text{ kg} \), while the proton is a hefty \( 1.673 \times 10^{-27} \text{ kg} \). This mass difference necessitates electrons to move much faster than protons to attain the same wavelength. This contrast in mass highlights the significance of each particle's unique properties in determining their velocity to achieve specific quantum characteristics like wavelength.

Manipulating the de Broglie equation \( \lambda = \frac{h}{mv} \), it becomes apparent that even small changes in mass can make substantial differences in speed calculations when matching wavelengths. Consequently, particle mass is not simply a static trait—it's a crucial determinant of a particle's quantum mechanical behavior.

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Most popular questions from this chapter

A photon of red light (wavelength \(=720 \mathrm{nm}\) ) and a Ping-Pong ball (mass \(=2.2 \times 10^{-3} \mathrm{kg}\) ) have the same momentum. At what speed is the ball moving?

The minimum uncertainty \(\Delta y\) in the position \(y\) of a particle is equal to its de Broglie wavelength. Determine the minimum uncertainty in the speed of the particle, where this minimum uncertainty \(\Delta v_{y}\) is expressed as a percentage of the particle's speed \(v_{y}\) (Percentage \(=\frac{\Delta v_{y}}{v_{y}} \times 100 \%\)) Assume that relativistic effects can be ignored.

A photon of wavelength \(0.45000 \mathrm{nm}\) strikes a free electron that is initially at rest. The photon is scattered straight backward. What is the speed of the recoil electron after the collision?

19\. E MMH An incident X-ray photon of wavelength \(0.2750 \mathrm{nm}\) is scattered from an electron that is initially at rest. The photon is scattered at an angle of \(\theta=180.0^{\circ}\) in Animated Figure 29.10 and has a wavelength of \(0.2825 \mathrm{nm}\) Use the conservation of linear momentum to find the momentum gained by the electron.

Multiple-concept Example 3 reviews the concepts necessary to solve this problem. Radiation with a wavelength of 238 nm shines on a metal surface and ejects electrons that have a maximum speed of \(3.75 \times 10^{5} \mathrm{m} / \mathrm{s}\) Which one of the following metals is it, the values in parentheses being the work functions: potassium \((2.24 \mathrm{eV}),\) calcium \((2.71 \mathrm{eV}),\) uranium \((3.63 \mathrm{eV}),\) aluminum \((4.08 \mathrm{eV}),\) or gold \((4.82 \mathrm{eV}) ?\)

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