What is Path difference: Definition and 35 Discussions
In optics, optical path length (OPL) or optical distance is the product of the geometric length of the path followed by light through a given system, and the refractive index of the medium through which it propagates. In many textbooks, it is symbolically written as Λ. A difference in optical path length between two paths is often called the optical path difference (OPD). OPL and OPD are important because they determine the phase of the light and governs interference and diffraction of light as it propagates.
I understand the equation (path difference)/wavelength x 2pi = phase difference, but in this case I do not know how changing the distance of H from the source will affect the path difference. In addition to this, does minima refer to 0 amplitude (complete destructive interference) or does minima...
For this
I am trying to prove that angle theta between PQ and QO is equal to theta highlighted so that I know I can use theta is the path difference formula. I assume that the rays ##r_1## and ##r_2## are parallel since ##L >> d##
My proof gives that the two thetas are equal, however I am...
My attempt:
I think ##x## is the path difference so by using trigonometry, I got ##x=d \sin \theta##
But my teacher said the answer is ##d \cos \theta##
What is my mistake? Thanks
Edit: Sorry, I found my mistake. My ##x## is not the path difference
I already have the solution in front of me, I am wondering why there is a difference in the formula for path difference. I've attached the problem as well to show the Figure.
What I am struggling to grasp is why the path difference for the angles closer to A is dsin(Θ) = (m+1/4)λ while the path...
Homework Statement
Homework Equations
Path difference is nλ at maxima, (n+0.5)λ at minima
The Attempt at a Solution
I think the phase difference between S1 and S2 is not 0 anymore, because the wave effectively takes a longer distance by going through S2. Thus, there is no longer a central...
1. Homework Statement
Two speakers S1
and S2 derived by the same amplifier and placed at y=1
and y = - 1.The speakers vibrate in phase at 600 Hz. A man stands on the x-axis at a very large distance from the origin and starts moving parallel to the Y - axis. The speed of sound in air is 330ms-1...
Hi, would it be possible to explain to me how does wave length, phase difference and path difference all link as I'm struggling with calculations involving these three things.
Why the center of Newton's ring is dark? though I am thinking the path difference in the center is zero between two reflected rays...
so,I will be glad if you give the correct information about that...
Homework Statement
Two antennas located at points A and B are broadcasting radio waves of frequency 98.0 MHz, perfectly in phase with each other. The two antennas are separated by a distance d= 6.20 m. An observer, P, is located on the x axis, a distance x= 60.0 m from antenna A, so that APB...
Hey everybody,
Homework Statement :
[/B]
I came across a question discussing Young's Double Slit interference and was wondering how come when we diffract white light through the slits it gives us a central antinodal fringe that is also white?
The question itself came in parts firstly...
Homework Statement
In a Young’s two-slit experiment a piece of glass with an index of refraction and a thickness is placed in front of the upper slit. (a) Describe qualitatively what happens to the interference pattern. (b) Derive an expression for the intensity of the light at points on a...
Homework Statement
Homework EquationsThe Attempt at a Solution
I formed a right angle triangle between the arrow downwards,d, and perpendicular line x from arrow. As such, sin θ = x/d.
x= d sinθ
path difference: d sinθ/λ
My answer is C, but answer is B. Where did cos θ come from?
Homework Statement
A Michelson interferometer is illuminated with a laser with a wavelength of 514.5nm. A Haidinger fringe pattern is photographed with a lens of focal length 55mm. The diameter of the two adjacent circular fringes in the image are 1.53mm and 2.62mm.
How far would the mirror...
Homework Statement
A Michelson interferometer is illuminated with a laser with a wavelength of 514.5nm. A Haidinger fringe pattern is photographed with a lens of focal length 55mm. The diameter of the two adjacent circular fringes in the image are 1.53mm and 2.62mm.
How far would the mirror...
Homework Statement
i can't understand why the optical path diffrence is 2nt+0.5λ. why is it so? the 0.5λ is due to the path difference change of 180 degree of when it is reflected lower ray when it is reflected from the lower glass surface... why there's also phase change of 2nt. since both...
Hi everyone
Homework Statement
I'm trying to understand the Laue equation but I have problems unterstanding the derivation, especially one part in my textbook about the path difference (see attachment)
The Attempt at a Solution
My textbook says that the path difference here is...
Homework Statement
In this question, when S2 is covered with a very thin glass, the fringe move toward Y . why is it so?
Homework Equations
The Attempt at a Solution
SOme one help me with the OPD.
How is here the OPD=n2(AB + BC) -n1(AD)?
I am not confused with the introduction of 'n'..Rather the path length is confusing me..Why is there a negative sign?
Tricky Path Difference Problem in waves, help! (attachment)
Homework Statement
check the attachment
Homework Equations
none needed for part (d)
The Attempt at a Solution
the first three questions of part (c) i got them out. answers were
(c) (i) 2x10 ^8 ms–1
(ii)...
Hi,
This is a question from a homework which has stumped me:
Light is traveling along a fibre optic cable of refractive index 1.52, the refractive index of the cladding is 1.51 and the critical angle between the two is 82.
a) what is the most direct route for light along the fibre-optic cable...
Homework Statement
Two in-phase speakers 4.50 m apart in a plane are emitting 1690 Hz sound waves into a room where the speed of sound is 343 m/s. Consider a point that is 8.50 m in front of one of the speakers, perpendicular to the plane of the speakers. What is the path difference (in...
Homework Statement
The more I think about path difference, the more confused I get.
First of all, HOW DO PEOPLE know that the path difference is dsinθ? Why do we draw a line coming from the first ray that is PERPENDICULAR to the second ray when determining path difference?
Please see...
Hello,
What are phase difference and path difference?
Can you give me a simple explanation so that I could imagine
It would be great if there are some illustrations
Thanks
I was doing a past paper earlier and i got a question about cold spots in microwaves and i needed to calculate path difference the question was:
---------|------->S<---------|--------- Explain why a cold spot is formed at S
18cm | 6cm. 12cm | 30cm
The question showed the...
Attached is the problem and solution for part B, can someone please explain how they obtain the equation for part B, i don't see why they take the root.
Thank you.
Homework Statement
[PLAIN]http://img153.imageshack.us/img153/8149/97578282.jpg
My textbook states that:
"Points P₁ and P₂ are both on antinodal lines. The length of the path traveled by wave 1 from its source (S₁) to point P₁ is two wavelengths. The length of the path traveled by wave 2 from its source (S₂) to point P₁ is three wavelengths. The path difference (pd) is...
take it as em waves.
if the path difference is nlambda, where n is an integer, the interference will be a constructive one.
if the difference is (n+1/2)lambda, it'll be distructive.
what's it if the difference is neither nlambda nor (n+1/2)lambda?
thanks.
Path Difference in Lenses...
A convex lens will converge all rays parallel to the optical axis to the focus.
Now obviously different rays at different distances from the optical axis will travel different distances in reaching the focus.
So why does this not create any path difference between...
Hi
I'm trying to understand how the Fabry-Perot etalon works for an experiment regarding the Zeeman effect.
Looking at the image could anyone tell me why the path difference in the etalon is \Delta l = 2t \cos{\theta}? In my head, the path difference is \Delta l = 2t/\cos{\theta}, in other...
Hi!
I hope I'm posting in the right place!
In the destructive interference of waves and solving for the path difference, I"m confused at when we should use m+1/2 vs. m-1/2 ( so the eq'n is PD=(m+1/2)lambda or PD=(m-1/2) lambda
Any insight would be greatly appreciated! :)
thanks!
respected members,
could anyone explain the difference between path difference and phase difference ? what does the term phase exactly mean? thanks in advance
1. Homework Statement
A wave front moving horizontally encounters a block of glass that has an index of refraction of 1.50 in its upper half and an index of refraction of 1.25 in its lower half. The wavelength of the wave front in air is 700 nm. At what lengths would the glass block cause...
Homework Statement
A wave front moving horizontally encounters a block of glass that has an index of refraction of 1.50 in its upper half and an index of refraction of 1.25 in its lower half. The wavelength of the wave front in air is 700 nm. At what lengths would the glass block cause...