how deep is the mud depends on who you ask This is a topic that many people are looking for. amritsang.org is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, amritsang.org would like to introduce to you Why does light bend when it enters glass?. Following along are instructions in the video below:
The world around us is a smorgasbord of beliefs claims rules and norms about how how we should live and behave. Its important to tease apart. These factors so can put them in their proper place.
Otherwise. It can be hard to know what to do especially. When some of these requirements.
Contradict others. Lets talk about three different categories of demands on how we should live ethics morality and law laws are formal rules that govern how we behave as members of a society. They specify what we must do and more frequently.
What we must not do they upheld and applied by the state and the court system and their role is to create a basic enforceable standard of behavior. But the law has a much narrower focus than either morality or ethics laws can be just or unjust and a subject to ethical assessment. Plus.
There are some matters about which the law will be silent. But where morality and ethics have a lot to say for example. The law is of no use if youre trying to decide whether to speak up when you hear a friend make a racist joke.
But ideas about whats good and right will still guide our judgement here morality refers to an informal framework of values principles beliefs customs and ways of living morality arent usually enforced by the state but there are often social pressures to conform to moral norms. Some people consider themselves to be so strongly bound by certain moral codes that even to question the moral system would be wrong. Some examples of morality include christianity.
Stoicism and buddhism each of these provides a set of answers to basic ethical questions. Like how should i live. And what should i do many people inherit their morality from their family community or culture.
Its rare for someone to shop around for the morality that most closely fits their personal beliefs. Usually the process of moral formation is unconscious. Whats its morality apart from ethics is that you can apply a morality as a matter of habit without having to think you can simply obey or follow instructions from those who claim moral authority.
Within a particular tradition and for some people this is enough maybe a world of habitually virtuous individuals is better than one. Where people are habitually vicious plus. Having a coherent consistent account of how to live can be a source of comfort especially in a complex and uncertain world.
But there is also a risk in living. What the greek philosopher socrates. Called an unexamined life.
If we just accept a ready made answer to the question of how we should live. We might live our whole lives under a moral system. Which if wed thought about it we would have rejected in part or in full.
This is where ethics comes in ethics is a branch of philosophy that aims to answer the basic question. What should i do its a process of reflection in which peoples decisions are shaped by their values principles and purpose. Rather than unthinking habits or social conventions.
Our values principles and purpose are what give us a sense of whats good right and meaningful in our lives. They serve as a reference point for all the possible courses of action. We could choose on this definition an ethical decision is one based on conscious reflection.
And which gives effect to our values principles and purpose in pursuit of a proper goal. It can be tempting to see law morality and ethics. As more or less the same.
We might think that so long as were fulfilling our legal or moral obligations. We can consider ourselves ethical in reality. There is more to ethics than morality and law ethics.
Requires us to think about issues. The law cant or doesnt address. It puts moral systems.
Under the microscope to see if they hold up in an ideal world our ethical beliefs shape. The kinds of laws and moral systems. Our society develops.
When our conscious reflective ethical views on whats good and right change. We ought to change the laws to reflect them and likewise our morality should evolve in response to insights generated from ethical reflection. But we can only do this if we have a toolkit that keeps open questions to do with what is good and right and that toolkit thats ethics you diers are rigid then the first soldier hitting mud puts a torque on the entire line and that would work the problem is that this torque means that the soldiers on the top of the screen move faster.
Which is to say that if it were light this part of the beam of light would have to move faster than light. So this explanation doesnt work either okay so far. We have a non explanation and a wrong explanation what about huygenss principle huygenss principle named after dutch physicist christian huygens depends crucially on the wave nature of light.
We know that when a wave encounters. A small gap. The wave passes through the gap and spreads out this principle is called diffraction and its universal to all waves.
If waves hit more than one gap each gap will allow waves to pass through and make ringlets. The waves from each gap can interfere with one another with the waves either adding to or subtracting from one another in this animation. The lines show the position of the peak of the waves showing how the waves add together is perhaps easier looking at them from the side.
When the peak of two waves. Encounter. One another the result is a single and bigger wave and when a peak of one wave hits the trough of another wave.
They can cancel each other out entirely. What huygens claimed is that there is no need for gaps. Each and every spot on a wave was acting like it went through a gap and was spreading out.
Now we can take that idea and have waves moving in one medium transition to another medium. Where the speed is different so we can take light traveling through air and shoot it through glass and because were interested in explaining the bending behavior. Well have light hit it at an angle.
Heres how the huygens explanation goes. What happens is that the wave peaks hit the glass at different times. The waves.
Then spread out and begin to interfere with one another notice that the wavelength is shorter in glass. Thats because the wave is moving more slowly. Where the lines accumulate.
Thats where the waves add to one another and they dont just line up in one spot. They line up again and again remember that the lines denote the top of the peaks of the waves. We can see that there are many places where the peaks line up.
We can overlay a couple of lines that show the direction that the wave is traveling and then remove the circular waves. And we see that this explanation seems to be doing a good job of predicting what happens when light goes from air to glass looks good right. But not so fast.
What happens. When we look at all of the waves coming through the glass. Things get a lot more complicated.
We do see that the waves add together to predict the direction that light moves in glass on the other hand. Thats not the only alignment for instance. We see other geometries where the waves line up there are the wave fronts that are going this way.
And then there are the wave fronts going this way so thats a problem it seems that this approach doesnt give a unique prediction. Okay we have ruled out fermats principle. The soldier analogy and huygenss principle.
These are all often seen as explanations of the cause of refraction given by people who really do know. Some physics. So whats the real answer.
It turns out that the only way to really answer. The question of why light bends when it goes from air to glass is to get serious about the nature of light and to embrace the fact that it is made of oscillating electromagnetic fields. And that means you need maxwells equations because this isnt a full blown physics class.
Im going to focus only on the electric fields and im not going to do the derivation because thats the fun part ill leave that to you. But the big ideas are actually pretty straightforward you start with maxwells equations. Which are always beautiful to see theyre a little scary looking.
But the question we are trying to answer is an easy one which makes the whole thing a lot simpler than youd imagine in fact were going to need only the bottom two equations. So lets see whats going on we start with light going from air to glass hitting the surface at an angle in our figure. We can replace the waves with the direction of motion.
Now it turns out that the electric field of light is perpendicular to the direction that light is traveling and we can add that field direction to the diagram and its very important to remember that this field has a component both parallel to the surface of the glass. And one that is perpendicular to the glass. And here is where maxwells equations come into play two copies of the equations are written here.
One that covers when light is traveling in air and one where it is traveling in glass. So here is the key point. The surface belongs to both the air region and the glass region this means that at the surface.
The equations on the top and the equations at the bottom have to apply and with a little bit of calculus you can find two important restrictions. The first is that the electric field parallel to the surface of the glass has to be the same in the air and glass and similarly perpendicular to the surface. What has to be the same is the electric field times.
This epsilon. Which is different for each material and depends on its molecular makeup. We can then manipulate these equations to see what the electric fields in glass should look like because epsilon is bigger in glass than in air that means that the perpendicular electric field in glass has to be smaller than it is in air now we remember that the direction that light travels is perpendicular to the electric field.
So we can put in an arrow to show the direction light must travel in the glass and finally we can see what light does when it enters glass or water or any transparent medium. It bends and the reason that it bends is because the epsilon in glass is bigger than in air. Okay.
What i just showed. You is an equation thing youre probably asking yourself what that epsilon actually physically means. Its there because of how the electric fields from the light interacts with matter in the glass.
You start out with glass with no electric field in it the glass has charges in it but theyre arranged in a random way. But when you send light in you impose an electric field on it that field makes the charges move around which sets up a counterbalancing electric field from the charges. The result is that the electric field in the glass is lower than it is in air because of how the electric field from the glass is in the opposite direction.
And this is the reason that the perpendicular electric field is lower in glass and that my friends is why light bends when it goes from air to glass. Its not because of many of the ordinary explanations. Its because of how light interacts with glass and changes the glasss properties and its because the electric field inside the glass is affected by the arrangements of atoms and molecules in the glass.
When light hits it its the same reason. Why light slows down in matter inside matter. The electric field due to the light and the electric field due to the matter both have to be taken into account outside they dont and now you know some serious physics.
Okay so that was a very long video it kind of had to be to cover the many incomplete or wrong explanations and then explain the correct cause and i imagine some of you will ask about the quantum explanation. Which is similar to the one. I told you here using maxwells equations.
Except using the energy and momentum of the photons instead. Theres always more to learn in physics. Always more and you knew that because of course physics is everything.
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