Normal incidence of light on a denser medium

  • B
  • Thread starter akhila_k
  • Start date
  • #1
13
1

Main Question or Discussion Point

When light, traveling through a rarer medium, gets reflected off at an interface with a medium of higher refractive index, it suffers a phase shift of half-wavelength. Now if it was normal incidence, the phase-shifted light would retrace its path. Does that mean the wave would cancel out?
 

Answers and Replies

  • #2
sophiecentaur
Science Advisor
Gold Member
24,673
4,549
When light, traveling through a rarer medium, gets reflected off at an interface with a medium of higher refractive index, it suffers a phase shift of half-wavelength. Now if it was normal incidence, the phase-shifted light would retrace its path. Does that mean the wave would cancel out?
The boundary conditions at the interface insist that the waves cancel out. As you look further away from the interface you pass through regions where the waves augment and cancel - i.e. a standing wave pattern. Power flows to the right and to the left. You don't actually lose any Power.
 
  • Like
Likes akhila_k
  • #3
13
1
The boundary conditions at the interface insist that the waves cancel out. As you look further away from the interface you pass through regions where the waves augment and cancel - i.e. a standing wave pattern. Power flows to the right and to the left. You don't actually lose any Power.
Okay. Thank you. Now if the phase difference was zero, the resultant would still be a standing wave, but now there will be an antinode at the interface instead of a node as in the previous case. Is that right?
 
  • #4
sophiecentaur
Science Advisor
Gold Member
24,673
4,549
Right. It's due to the boundary conditions. A good example is the reflection of sound at the end of a pipe if it is closed or if it is open. You still get a standing wave but with a node or antinode at the end - depending.
 
  • Like
Likes akhila_k
  • #5
13
1
Right. It's due to the boundary conditions. A good example is the reflection of sound at the end of a pipe if it is closed or if it is open. You still get a standing wave but with a node or antinode at the end - depending.
Thank you. That was really helpful.
 
  • Like
Likes sophiecentaur
  • #6
sophiecentaur
Science Advisor
Gold Member
24,673
4,549
Boundary conditions rule!!! :smile:
 
  • Like
Likes akhila_k

Related Threads on Normal incidence of light on a denser medium

Replies
2
Views
5K
Replies
6
Views
3K
Replies
3
Views
13K
  • Last Post
Replies
11
Views
5K
  • Last Post
Replies
10
Views
11K
Replies
0
Views
2K
Replies
3
Views
5K
  • Last Post
Replies
14
Views
3K
  • Last Post
Replies
4
Views
1K
Top