Possible Difference in Light Paths for Coherent Sources at Point P?

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Homework Help Overview

The discussion revolves around a problem involving two coherent light sources and the conditions for interference at a point P, where the intensity is noted to be zero. Participants are exploring the implications of path length differences between the two sources and how these relate to interference patterns.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are attempting to understand the conditions necessary for interference to occur, particularly focusing on the path length difference that leads to destructive interference. Questions about the nature of the diagram and the relationship between the distances provided are also raised.

Discussion Status

The discussion is ongoing, with participants providing hints and asking clarifying questions. Some guidance regarding the concept of interference and the need for coherent sources has been offered, but there is no explicit consensus on the interpretation of the problem or the diagram.

Contextual Notes

There is mention of a diagram that is not provided, which may be critical for understanding the problem. Participants are also navigating the implications of the specific distances given (4.3 cm and 5.1 cm) in relation to the path length difference.

jullrich
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Homework Statement

: The diagram represents two coherent light sources emitting light of equal intensity and wavelength. The intensity of the light at point P is zero. Which of the following could be the difference in path length taken by the light in traveling from each source to point P?



Homework Equations

: the diagram looks like a 3-4-5 triangle with the short side left off and where to two lines cross for a point on the opposite side to be point P. The length of one side is 4.3 cm and the other side is 5.1 cm.



The Attempt at a Solution

: we know the answer is 1/2 lamda but have no idea how to how solve this ... please help

 
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jullrich said:

Homework Statement

: The diagram represents two coherent light sources emitting light of equal intensity and wavelength. The intensity of the light at point P is zero. Which of the following could be the difference in path length taken by the light in traveling from each source to point P?



Homework Equations

: the diagram looks like a 3-4-5 triangle with the short side left off and where to two lines cross for a point on the opposite side to be point P. The length of one side is 4.3 cm and the other side is 5.1 cm.



The Attempt at a Solution

: we know the answer is 1/2 lamda but have no idea how to how solve this ... please help

Welcome to PF!

Do you know what is interference and what conditions must be applied for interference to occur?
 
No interference and no conditions.
 
What do you mean no interference? You haven't studied it or it isn't the case here?

Check out when waves interfere to cancel each other. To understand this, you must know how to plot a graph for a wave. And if you could upload the diagram (the actual one or sketched in paint), it would be a bit easier to discuss the exercise. Just remember that nobody will solve it for you. People will only give you hints to help you better understand the exercise and solve it yourself.
 
The diagram looks like two rays from the same origin point.
The end of the rays would be the light itself.
 
Well, you got me confused. At first you say that the diagram is a triangle but now you say that waves originate from the same point and meet at point P. For two waves two have an interference minimum (cancel out each other, hence have an intensity sum zero at an intersection point) they must be coherent and one must have the distance traveled by lamda/2 more. As much as I understand from your description of the exercise, this is what's asked. However, you have these 4.3 and 5.1 and I'm rather confused why.
 

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