Refraction at a spherical surface

  • Thread starter stpmmaths
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  • #1
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Homework Statement



attachment.php?attachmentid=20107&stc=1&d=1250245914.jpg


Homework Equations





The Attempt at a Solution



I was kind of confuse with the use of refractive index.

For the first part of question, n1 = 1.00 and n2 = 1.50. From what I know, the object is at vacuum so the n1 = 1.00.

But why for the second part of the question, n1 = 1.50 and n2 = 1.00 ? After the first refracting surface, the image should be at the vacuum too. But why we use n1 = 1.50?
 

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Answers and Replies

  • #2
tiny-tim
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Welcome to PF!

Hi stpmmaths! Welcome to PF! :smile:
I was kind of confuse with the use of refractive index.

For the first part of question, n1 = 1.00 and n2 = 1.50. From what I know, the object is at vacuum so the n1 = 1.00.

But why for the second part of the question, n1 = 1.50 and n2 = 1.00 ? After the first refracting surface, the image should be at the vacuum too. But why we use n1 = 1.50?

(I can't see your attachment yet, but …)

I assume that the light starts by going into the sphere from the air (or vacuum), so it's going from n = 1 to n = 1.5;

then it travels through the sphere (n = 1.5) until it hits the opposite surface and comes out again, so it's going from n = 1.5 to n = 1. :wink:
 
  • #3
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Hi stpmmaths! Welcome to PF! :smile:


(I can't see your attachment yet, but …)

I assume that the light starts by going into the sphere from the air (or vacuum), so it's going from n = 1 to n = 1.5;

then it travels through the sphere (n = 1.5) until it hits the opposite surface and comes out again, so it's going from n = 1.5 to n = 1. :wink:

Ok..I understand a bit.

Now I came across with another question similar to this question(quite similar)

Quenstion:
attachment.php?attachmentid=20113&stc=1&d=1250304700.jpg

Answer:
attachment.php?attachmentid=20114&stc=1&d=1250304700.jpg


Why the n1 is 1.50 if we say the light starts from vacuum?:confused:
 

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  • #4
tiny-tim
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Why the n1 is 1.50 if we say the light starts from vacuum?:confused:

Because the light starts from the coin, inside the sphere, not from vacuum. :wink:
 
  • #5
Redbelly98
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Why the n1 is 1.50 if we say the light starts from vacuum?:confused:

Look carefully at the arrows in the figure. Where do they start from?

EDIT: to clarify, look at the interface where the two rays meet. The ray arrows indicate they go from the glass into the air.

p.s. Hello tiny-tim!
 
  • #6
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Oo, I got it.
Thanks everyone.
 

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