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Q18E

Expert-verified
Modern Physics
Found in: Page 134
Modern Physics

Modern Physics

Book edition 2nd Edition
Author(s) Randy Harris
Pages 633 pages
ISBN 9780805303087

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Short Answer

A particle is “thermal” if it is in equilibrium with its surroundings – its average kinetic energy would be 32kBT . Show that the wavelength of a thermal particle is given by

λ=h3mkBT

As a result, were able to demonstrate that :

λ=h3mkBT

See the step by step solution

Step by Step Solution

Step 1:Given and unknowns.

Particle's average kinetic energy isKE=32kBT

λ=h3mkBT

Step 2: Concept Introduction

The following equation can be used to describe the de Broglie wavelength:

p=hλ.........(1)

When it comes to momentum, it's best to think of it this way:

p=mv .......(2)

The kinetic energy, on the other hand, can be expressed by the following equation:

KE=12mv2........(3)

Step 3:Expression for wavelength.

Get the expression for using Equations (1) and (2)λ :

hλ=mv

λ=hmv

Step 4: Expression for v.

Now use the average kinetic energy and Equation (3) to get the expression for the particle's speed because don't have one

KE=12mv2

KE=32kBT

12mv2=32kBT

v2=32kBTm

v=3kBTm

Step 5: Derived expression for v.

The generated expression is then plugged into the expression of λ:

λ=hmv=h(3kBTm)=h3mkBT

As a result, were able to demonstrate thatλ=h3mkBT

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