# Reflection and Refraction of Electromagnetic Waves at a Glass-Air Interface

• Zaheer
In summary, Zaheer attempted to solve for the reflected electric field, but was not able to. He suggests that someone else help him.
Zaheer
1. Consider a y-polarized electromagnetic wave with vacuum wavelength 600nm that is propagating in glass and then incident on a glass-air interface; use n=1.4 for glass. Take the interface surface to be the y-z plane, and the plane of incidence to be the x-z plane. Consider 2 incident angles, 45, and 80 degrees. Take the amplitude of the incident field to be Eo.

Write complete expressions for the reflected and transmitted electric fields If there are any evanescent fields, determine the depth of penetration into air.

## Homework Equations

I've determined the E-field to be perpendicular to the plane of incidence so
r(perpendicular)= (E0r/E0i)= (nicos(thetai)-ntcos(thetat))/nicos(thetai)+ntcos(thetat)
then snells law nisin(thetai)=ntsin(thetat)
Then Possibly the O.P.L= INtegral from S to P n(s)ds
OPL/lamda0=s/lamda
t=OPL/c
where OPL is the Optical path length, n(s) is the index of refraction incident as a function of position.

## The Attempt at a Solution

Okay, so I began with attempting to solve for the reflected E-field. So I first used Case 1 where thetai= 45. I solved for theta t, and got 30.3 degrees. then solved for the reflected amplitude and got -o.5016 (obtained by plugging in values to the E0r equation. So I wrote the Reflectance to be the following

r(perpendicualar)= -0.5016/Eo. I don't think that's right at all due to the fact that it should also refract in glass, then reflect so off air, and refract in air, I only took the case where it relfects of glass. I am almost completley stuck, tried reviewing sections to try and understand this problem better but haven't been able to. Could anyone just help shoot me in the right direction please? Thanks.

HELPPPPPPPP
AHHHH

BUMP

HOLY bump again. At this point I've done the problem. I just want some reassurance.

Hi Zaheer could you please respond to my messege I believe you must have been taking phy2311 at uottawa, because I had been searching for answers to the assignments and usually come across your posts, could you please write back to me if you find a minute I have a question from you. Thank you in advance.

## 1. What is the difference between a wave and a particle?

A wave is a disturbance that travels through a medium, whereas a particle is a small unit of matter that has mass and occupies space. Waves have properties such as wavelength and frequency, while particles have properties such as mass and charge. In some cases, light can behave as both a wave and a particle, known as wave-particle duality.

## 2. How does light travel through different mediums?

Light can travel through different mediums such as air, water, or glass because it is an electromagnetic wave. When light enters a medium with a different density, it will either speed up or slow down, causing it to change direction. This phenomenon is known as refraction.

## 3. What is the difference between reflection and refraction?

Reflection is the bouncing back of light when it hits a surface, while refraction is the bending of light as it passes through a medium with a different density. Reflection follows the law of reflection, which states that the angle of incidence is equal to the angle of reflection. Refraction follows Snell's Law, which relates the angle of incidence and the angle of refraction to the speed of light in different mediums.

## 4. How do lenses work in optics?

Lenses are transparent objects made of glass or plastic that can refract light and change its direction. Convex lenses, such as those found in magnifying glasses, converge light to a focal point, while concave lenses diverge light. This property of lenses is used in various optical instruments, such as microscopes and telescopes.

## 5. What is the difference between constructive and destructive interference?

Interference occurs when two or more waves overlap and combine. Constructive interference happens when the waves are in phase, meaning their crests and troughs align, resulting in a larger wave. Destructive interference occurs when the waves are out of phase, resulting in a smaller or canceled wave. This phenomenon is essential in understanding the behavior of light, sound, and other waves.

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