MCQ : Comparing characteristics of two photons

  • Thread starter Jahnavi
  • Start date
  • #1
Jahnavi
848
102

Homework Statement


Two photons.jpg


Homework Equations




The Attempt at a Solution



I am surely making some very silly mistake in this problem . Presuming linear momenta means magnitude of momentum , to me all four options look correct .

a) since wavelengths are same , energy is same which means momentum is same .option a) is correct .

Similarly b) , c) , d) are correct .

Or is it that the question is considering momentum as a vector (which it is ) but generally in these problems only magnitude of momentum is considered .

If this is the case , option d) is correct .

Please let me know which is correct .
 

Attachments

  • Two photons.jpg
    Two photons.jpg
    32.4 KB · Views: 522

Answers and Replies

  • #2
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
11,834
4,849
I think the question wants you to consider momentum as a vector. Compare (a) and (d). Only one of them can be correct.
 
  • #3
Jahnavi
848
102
I think the question wants you to consider momentum as a vector. Compare (a) and (d). Only one of them can be correct.

I think d) will be correct .
 
  • #4
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
11,834
4,849
I agree.
 
  • #5
Jahnavi
848
102
In the relation E = Pc for a photon, are both the terms on RHS (momentum and speed ) treated as vectors and is it that a dot product is taken so as to get the energy term E ?
 
  • #6
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
11,834
4,849
In the relation E = Pc for a photon, are both the terms on RHS (momentum and speed ) treated as vectors and is it that a dot product is taken so as to get the energy term E ?
##E=pc## is a scalar equation containing scalars only. I cannot think of a situation in which the momentum and the velocity are in different directions. Can you?
 
  • #7
Jahnavi
848
102
No :smile:

I asked because E = Pc doesn't involve vectors whereas in the OP direction of momentum vector was to be considered while relating to wavelength (energy ) .
 
  • #8
kuruman
Science Advisor
Homework Helper
Insights Author
Gold Member
2021 Award
11,834
4,849
No :smile:
I asked because E = Pc doesn't involve vectors whereas in the OP direction of momentum vector was to be considered while relating to wavelength (energy ) .
Yes, but as you have gathered already by now only (d) is necessarily correct. However, all four answers would be correct if the two photons travel in the same direction. The way one answers this question depends on one's assumptions. In my opinion it's not a well-crafted question because it leaves room for ambiguity. A well-crafted ##N## choice question should have one necessarily correct answer and ##N-1## choices that cannot possibly be correct.
 
Last edited:
  • #9
Jahnavi
848
102
Thanks !
 

Suggested for: MCQ : Comparing characteristics of two photons

  • Last Post
Replies
13
Views
950
Replies
4
Views
2K
Replies
2
Views
4K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
10
Views
639
Replies
5
Views
2K
Replies
0
Views
1K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
1K
  • Last Post
Replies
2
Views
3K
Top