Why light can't penetrate the prism with 45 degree angle

In summary, light can penetrate with 0 degree of normal of surface and it is reflected with 45 degree of normal of surface. as it seems in illustration. Density of glass is more than air.
  • #1
Gazi
17
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why light can't penetrate the prism with 45 degree angle?
 
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  • #3
Gazi said:
why light can't penetrate the prism with 45 degree angle?
You have to specify other details, otherwise the question becomes invalid because there are many situations in which a light can pass through a 45 degree prism.
 
  • #4
Let say, light comes with wide angle like 60 degree of normal of surface and reflect with same angle. there is a formula about that in the web page. why it can't penetrate the prism with wide angle? difference of density between prism and air is a factor, is there another reason for it
 
  • #5
Gazi said:
Let say, light comes with wide angle like 60 degree of normal of surface and reflect with same angle. there is a formula about that in the web page. why it can't penetrate the prism with wide angle?
That still does not add that much to give a unique solution to the original question. Other details that should be given are the incident angle, the direction of the incoming ray (i.e. from above or below the normal line), and prism material.
 
  • #6
it's not a unique question in fact. it's a general question about the situation of light can't penetrate prism and reflect back. one reason is difference of density...
 
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  • #7
The way you phrase your question makes it as if no matter what other parameters are, so long as the prism apex angle is 45 degree, any incoming light cannot come out of the prism in the other side. I can have a situation with prism apex angle other than 45 degree but the light cannot penetrate the prism.
Gazi said:
one reason is difference of density...
Density of the material? You mean the refractive indices? Then it should also have been stated in the beginning as a condition, along with other parameters which makes the question unambiguous.
 
  • #8
It sure can "penetrate". Look at this case:

refr-90dev-prism.jpg

You may have in mind something but definitely did not describe it with enough detail.
 
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  • #9
Gazi said:
it's not a unique question in fact. it's a general question about the situation of light can't penetrate prism and reflect back. one reason is difference of density...
Yep, it sure is. It is, as others have pointed out, SUCH a general question that it does not have an answer, or looked at differently, it has lots of answers. That's why everyone is pressing you to ask a more specific question that perhaps DOES have an answer.
 
  • #10
nasu said:
It sure can "penetrate". Look at this case:

refr-90dev-prism.jpg

You may have in mind something but definitely did not describe it with enough detail.
Light can penetrate with 0 degree of normal of surface and it is reflected with 45 degree of normal of surface. as it seems in illustration. Density of glass is more than air. I don't ask a specific question about that. my point what is the reason of reflection of light depends on angle of it
 
  • #11
In fact, what is called total internal reflection is a phenomenon where some light refracts, not being, then, exactly " total" this reflection.
There appears an evanescent wave at the other side of the prism, which is a patern of intensity that falls exponentially with the distance from the walls of the prism.
Nevertheless, I see that there is space for doubts with respect to the physics of this special case in the chapter of "refraction".

Best wishes,

DaTario
 
  • #12
Snell's Law?
 
  • #13
Gazi said:
my point what is the reason of reflection of light depends on angle of it
"Reflection" is not a physical quantity, so there is no mathematical relations which can associated to it. Nevertheless there are two quantities which may be related to the phenomena of light reflection: reflection coefficient and the angle of reflection. The dependency of both of these quantities on the incident angle can be derived through the Maxwell equations at the boundary of the two media.
 

1. Why does light bend when it enters a prism at a 45 degree angle?

Light bends when it enters a prism at a 45 degree angle because of a phenomenon called refraction. When light travels from one medium to another, its speed changes, causing it to bend or refract. This change in speed is due to the difference in the density of the two mediums.

2. Why can't light penetrate the prism at a 45 degree angle?

Light cannot penetrate the prism at a 45 degree angle because it undergoes total internal reflection when it hits the second surface of the prism. This means that all of the light is reflected back into the prism instead of passing through it.

3. Why does the angle of incidence matter when light enters a prism?

The angle of incidence is the angle at which light enters the prism. This angle is important because it determines the angle at which the light will be refracted and the amount of bending that will occur. At a 45 degree angle of incidence, light will undergo total internal reflection and cannot pass through the prism.

4. Is there a specific reason why light cannot pass through a prism at a 45 degree angle?

Yes, there is a specific reason why light cannot pass through a prism at a 45 degree angle. This angle is known as the critical angle, and it is the angle at which light will undergo total internal reflection. This phenomenon occurs when the angle of incidence is greater than the critical angle for a particular medium.

5. How does the shape of a prism affect the angle at which light can pass through it?

The shape of a prism plays a crucial role in determining the angle at which light can pass through it. A 45 degree angle is the maximum angle at which light can enter a prism and still pass through the second surface. If the angle is greater than 45 degrees, the light will undergo total internal reflection and cannot pass through the prism.

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