PHYS 1C Lecture Notes - Lecture 11: Thin-Film Interference, Soap Bubble, Transverse Wave

54 views2 pages

coffeecamel142

4 May 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

When light passes from one medium to another, the

wavelength will change because the speed of light is

different in the two media

The index of refraction, n, of a medium can be defined

Index of Refraction

As light travels from one medium to another, the frequency does not

change

Both the wave speed and the wavelength do change

Frequency Between Media

Have you ever looked at a soap bubble and observed patterns of

different colors

Light wave interference can also be observed in thin films (such as an oil

film on water or soap bubbles)

The interference in thin films is caused by not only a path length

differnce but also a phase shift as the light ray reflects off of a different

medium

A light wave will undergo a phase change of 180 degrees upon reflection

from a medium of higher index of refraction than the one in which it was

traveling

So, a light wave traveling in air will undergo a 180 degree phase shifts if

it reflects off an oil surface

This is similar to the reflection of a transverse wave that we observed

earlier off of a rigid surface

A light wave will NOT undergo a phase change upon reflection from a

medium of lower index of refraction than the one in which it was

traveling

So a light wave traveling in oil will not undergo a phase shift if it reflects

off an air boundary

This is similar to the reflection of a transverse wave that we observed

earlier off of a free surface

Ray 1 (in air) reflects off the film surface and undergoes a phase

change of 180 degrees compared to the incident ray

○

With light incident on a thin film with another thin film of higher index of

refraction below the first:

Interference in thin films

(11) Lecture 27B Thin Film Interference

Friday, April 27, 2018

1:00 PM

week 4 Page 1

Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

When light passes from one medium to another, the wavelength will change because the speed of light is different in the two media. The index of refraction, n, of a medium can be defined. As light travels from one medium to another, the frequency does not change. Both the wave speed and the wavelength do change. Have you ever looked at a soap bubble and observed patterns of different colors. Light wave interference can also be observed in thin films (such as an oil film on water or soap bubbles) The interference in thin films is caused by not only a path length differnce but also a phase shift as the light ray reflects off of a different medium. A light wave will undergo a phase change of 180 degrees upon reflection from a medium of higher index of refraction than the one in which it was traveling.

Related Questions

Thepicture above shows a source of light in the lower medium (thepurple dot), with the light shining on the origin, which is markedby the position of the green dot. The horizontal axis is theinterface separating one medium from another. In this case, all ofthe light reflects back into the lower medium.
Choose all the correct statements about this situation from thelist below.
A.The lower medium (where the source is) has a larger index ofrefraction than the upper medium.
B.The lower medium has the same index of refraction as the uppermedium.
C.The lower medium has a smaller index of refraction than the uppermedium.
D.The angle of incidence in this case is greater than the criticalangle for total internal reflection to occur.
E.The angle of incidence in this case is smaller than the criticalangle for total internal reflection to occur.
F.If the light source was moved to the position of the red dot inthe upper medium, and the light was incident on the origin again,the light would definitely experience total internalreflection.
G.If the light source was moved to the position of the red dot inthe upper medium, and the light was incident on the origin again,some light would refract into the lower medium, traveling towardthe position of the purple dot.
H.If the light source was moved to the position of the red dot inthe upper medium, and the light was incident on the origin again,some light would refract into the lower medium, but the light wouldnot travel toward the position of the purple dot.

1)A light ray is incident on a reflecting surface. If the light ray makes a 25° angle with respect to the normal to the surface, what is the exact angle (in degrees) made by the reflected ray relative to the normal?

2)The light ray that makes the angle θ1' is the refracted ray (true or false?)

3)True or False: The Law of Reflection can be used to show how an image appears behind a mirror and it can also be used to determine where the image will be located.

4) Snell's law is another name for the

law of dispersion

law of reflection

law of refraction

5) A light ray incident on a block of glass makes an incident angle of 50.0° with the normal to the surface. The refracted ray in the block makes a 26.8° with the normal. What is the index of refraction of the glass?

A light ray traveling from a higher index of refraction medium into a lower index of refraction medium (for example, from water into the air) would bend away from the normal to the medium surface. When the refracted ray is parallel to the boundary of the medium, θ2= 90°. The incident angle, θ1, becomes θc, called the

viridianchinchilla179

1. A light ray is incident on a reflecting surface. If the light ray makes a 25° angle with respect to the normal to the surface, what is the exact angle (in degrees) made by the reflected ray relative to the normal?

2. The light ray that makes the angle θ₁' is the refracted ray (true or false?)

3. True or False: The Law of Reflection can be used to show how an image appears behind a mirror and it can also be used to determine where the image will be located.

4. Snell's law is another name for the

law of dispersion
law of reflection
law of refraction

5. A light ray incident on a block of glass makes an incident angle of 50.0° with the normal to the surface. The refracted ray in the block makes an 26.8° with the normal. What is the index of refraction of the glass?

6. A light ray traveling from a higher index of refraction medium into a lower index of refraction medium (for example, from water into air) would bend away from the normal to the medium surface. When the refracted ray is parallel to the boundary of the medium, θ₂= 90°. The incident angle, θ₁, becomes θ_c, called the

cauchy angle
critical angle
conjugate angle
classic angle

pearchinchilla839

PHYS 1C Lecture Notes - Lecture 11: Thin-Film Interference, Soap Bubble, Transverse Wave

Document Summary

Get access

Related textbook solutions

Physics: Principles with Applications

Related Documents

PHYS 1C Chapter Notes - Chapter 25: Specular Reflection, Diffuse Reflection, Refraction

PHYS 1C Lecture Notes - Lecture 13: Double-Slit Experiment, Specular Reflection, Refraction

PHYS 1C Lecture Notes - Lecture 8: Photon, Vacuum Permittivity, Gamma Ray

Related Questions