KE of Electrons to give same theta as light in double slit diffraction

Click For Summary

Homework Help Overview

The discussion revolves around the problem of determining the kinetic energy of electrons required to produce an interference pattern similar to that of coherent light passing through a double slit. The focus is on achieving the same angle for the second-order maximum in the interference pattern.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between the wavelength of electrons and light, considering the use of equations involving momentum and kinetic energy. Questions arise regarding the application of these equations to electrons versus photons.

Discussion Status

Some participants have provided guidance on using momentum to find kinetic energy, while others have clarified the distinction between equations applicable to photons and those relevant to electrons. The discussion has progressed with attempts to derive a relationship involving kinetic energy and wavelength.

Contextual Notes

There is mention of confusion regarding the necessary parameters for calculations, such as the speed of electrons and the relationship between momentum and kinetic energy. The original poster indicates a need for hints and pointers to guide their reasoning.

Silly Sausage
Messages
4
Reaction score
0

Homework Statement



Coherent light is passed through two narrow slits whose separation is d. The second-order bright fringe in the interference pattern is located at an angle of theta.

If electrons are used instead of light, what must the kinetic energy of the electrons be if they are to produce an interference pattern for which the second-order maximum is also at theta?

Homework Equations



No relevant equations givven

The Attempt at a Solution



Well, I started by saying that the wavelength of the electrons will be the same as the wavelength of light, and thought of using h=p lambda and then E=hf.

However I then confused myself because for h=p lamba I need the momentum and for that I need the speed. E=hf will give me kinetic energy wouldn't it? Can I please have some hints and pointers as to what direction I should be thinking in?
 
Physics news on Phys.org
Silly Sausage said:
Well, I started by saying that the wavelength of the electrons will be the same as the wavelength of light, and thought of using h=p lambda
Good. Use that to find the momentum of the electrons.
and then E=hf.
That would apply for photons, not electrons.

How does momentum relate to kinetic energy?
 
OK. I used Ek = p^2/(2m) and h=p lambda

to give Ek= h^2/(lambda^2*2m)

now do I use n lmbda = dsin theta?
 
done it! thanks guys!
 
Sounds good to me.
 

Similar threads

Undergrad Single vs. Double slit coherence clarification please
  • · Replies 10 ·
Replies
10
Views
2K
High School Disappearance of interference pattern in double slit
  • · Replies 12 ·
Replies
12
Views
2K
High School Explanation for bright fringes in Single Slit Diffraction
  • · Replies 4 ·
Replies
4
Views
2K
Young's double slit interference
  • · Replies 1 ·
Replies
1
Views
3K
Diffraction pattern from a grating
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad Double-slit experiment, determining which slit an electron passed thru
  • · Replies 26 ·
Replies
26
Views
3K
What Is the Maximum Slit Width in a Double Slit Experiment?
  • · Replies 4 ·
Replies
4
Views
2K
Double Slit Interference (slit width relevant)
  • · Replies 2 ·
Replies
2
Views
2K
Covering a slit in a diffraction grating - what happens?
  • · Replies 16 ·
Replies
16
Views
3K
High School Non-parallel double slit experiment
  • · Replies 4 ·
Replies
4
Views
2K