What is the correct way to draw this internal reflection

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    Internal Reflection
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Discussion Overview

The discussion revolves around the correct method for illustrating internal reflection in a specific scenario, focusing on the application of the laws of reflection. Participants are examining a drawing that depicts the reflection process and questioning its accuracy based on established principles.

Discussion Character

  • Debate/contested, Technical explanation

Main Points Raised

  • One participant questions why the answer suggests only 0 or 1 further reflection, arguing that the length of the path seems to require more reflections.
  • Another participant critiques the symmetry of the first reflection in the drawing, suggesting that the angles of incidence and reflection may not be equal as required by the laws of reflection.
  • A participant clarifies that the drawing in question is not their own but agrees it reflects their own drawing style.
  • Some participants assert that if the drawing does not adhere to the laws of reflection, it cannot be correct.
  • There is a suggestion that the drawing should be adjusted to comply with the laws of reflection to arrive at the correct answer.
  • One participant expresses a lack of motivation to draw it out but claims that their visual approximation appears acceptable.
  • A participant asks for opinions on the answer provided in the mark scheme, indicating a desire for validation or critique of that answer.

Areas of Agreement / Disagreement

Participants express disagreement regarding the accuracy of the drawing in relation to the laws of reflection. There is no consensus on the correct representation of the internal reflection, and multiple viewpoints on the drawing's validity are presented.

Contextual Notes

Some participants note potential issues with symmetry and adherence to the laws of reflection, but these concerns remain unresolved. The discussion does not clarify the specific conditions or assumptions underlying the mark scheme's answer.

Syndy
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The answer is saying the following,

initial reflection + 0 or 1 further reflection only, not at lower surface

must be straight and reach within 1cm of end.
---------
How come 0 or 1 reflection only ? The length is long to take only one reflection!

I also attached a photo of how I think it should be drawn.

Thank you for your help!
 
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Looking at your drawing, it seems to me that the first reflection is not symmetrical.. Did you draw a Normal and get the angles i and r the same.? Your picture seems to bring the first reflection to hit the lower surface much too soon. I could believe the 'real answer' more than yours. (That third reflection of yours looks even worse.)
 
Actually this is not my drawing . I found it in the internet but this is exactly the way I have drawn too.
 
Well, it can't be right if it doesn't follow the laws of reflection, can it?
 
I agree. It doesn't follow the law of reflection !
 
So it's wrong. Draw it so it does follow the law and you should get the right answer. :wink:
 
What do you think about the asnwer in the mark scheme?
 
I can't be bothered to draw it out but it looks OK when I do it 'by eye'. Have you drawn it out carefully and do you disagree with it?
 

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