Help! Confused on Ray Diagram for Exam Question

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Homework Help Overview

The discussion revolves around a ray diagram related to lenses, specifically focusing on the distinction between converging and diverging lenses. The original poster expresses confusion regarding their exam performance related to a ray diagram they drew, questioning whether their interpretation of the lens type was correct.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to clarify their understanding of ray diagrams for diverging and converging lenses, expressing uncertainty about their exam answer. Other participants question the adequacy of prior instruction on lens symbols and the overall teaching approach.

Discussion Status

The discussion includes various perspectives on the adequacy of the teaching methods and the clarity of the exam instructions. Some participants provide feedback on the original poster's confusion, while others emphasize the importance of textbooks as a resource for understanding.

Contextual Notes

Participants note a lack of prior instruction on lens symbols before the exam, which may have contributed to the confusion. There are references to the teaching style of the instructor, which some find inadequate, impacting students' preparedness for the exam.

Eveflutter
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Fairly simple question I'd like someone to help with please. My teacher has me confused so I figured I'd turn to the forums for help.

1. Alright, so in an exam we had a ray diagram to draw. "Complete the ray diagram shown in Figure 6" they said (I sketched a replica * thumbs up* hongjinyoungreferenceimsorry):
image.jpg


Alrighty. (No relevant equations so I'm jumping to step three)3. I attempted it because, you know, it was an exam. I drew these emerging rays in yellow:

image.jpg


However, after the exam, I realized I drew it wrong? The lens seemed to be a diverging one so I sulked thinking that I'd get it wrong. I reattempted all the questions in the exam at home and I drew this for this particular question:
image.jpg

Since the lens seems to be divergent, the rays should diverge, no?

But no! I received my exam paper and my teacher marked the exam ray diagram correct and gave me the two marks that came with it.

So I'd really appreciate it if someone would deliver me from this time of confusion. Does that really represent a diverging lens so the third picture is correct? Or is it a converging lens so that the second picture is correct?
Thanks in advance!
 
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I find it strange the symbols for the various lenses were not introduced before the exam. Did other students complain?
 
mfig said:
I find it strange the symbols for the various lenses were not introduced before the exam. Did other students complain?
Its not that strange, honestly, it's just how it is. You see, my teacher rarely ever attends classes and when he does, he reaches sometimes twenty minutes before the bell rings and simply lectures us on life goals, the expectations of us, and talks about the country's state. He hardly teaches. It's up to us to either go to paid classes outside school or dive into our textbooks and learn everything there. We've complained so many times but they haven't done anything about it. We asked other teachers about it and they said that he does this to every class, every year. It's unfair.

I learn from my textbook. They mainly focused on converging lenses and showed us ray diagrams for them.
 
mfig said:
I find it strange the symbols for the various lenses were not introduced before the exam. Did other students complain?
They drew the converging lenses like a ellipse-diamond mutant.
 
I do not think that this is the place to post opinions of teachers.
The answers and explanations to physics questions have nothing to do with the competence of teachers either here or elsewhere.
Text books are a good source of exlanation.
 
Eveflutter said:
So I'd really appreciate it if someone would deliver me from this time of confusion. Does that really represent a diverging lens so the third picture is correct?
Yes. Your exam answer should have been marked wrong.
 
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haruspex said:
Yes. Your exam answer should have been marked wrong.
Thanks!
 
lychette said:
I do not think that this is the place to post opinions of teachers.
The answers and explanations to physics questions have nothing to do with the competence of teachers either here or elsewhere.
Text books are a good source of exlanation.

"mfig" asked so I answered. But thanks, I'll keep you advice in mind for future threads. :ok:
And yeah, textbooks are great sources for explanations.
 

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