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Little Physics Excercise

Fkkize
Posts: 2,301
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7/14/2016 9:15:25 PM
Posted: 1 year ago
Had a physics exam today. Still feel like more of it, so here's a little excercise on ray optics for you guys.

All light rays entering a fibre optic cable through it's face side are to be totally internally reflected. What is the minimal refractive index the cable needs to have for this?
dylancatlow
Posts: 13,065
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7/14/2016 9:23:00 PM
Posted: 1 year ago
17 units. Now all you have to do is figure out how much goes into a unit, and you have your answer.
"In case anyone hasn't noticed it, the West is in extremis. The undertaker is checking his watch at the foot of its bed, and there's a sinister kettle of croaking, money-feathered vultures on the roof."
Fkkize
Posts: 2,301
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7/14/2016 9:27:08 PM
Posted: 1 year ago
At 7/14/2016 9:23:00 PM, dylancatlow wrote:
17 units. Now all you have to do is figure out how much goes into a unit, and you have your answer.

That's how I pass all my tests
MagicAintReal
Posts: 1,018
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7/17/2016 1:29:51 PM
Posted: 1 year ago
At 7/14/2016 9:15:25 PM, Fkkize wrote:
Had a physics exam today. Still feel like more of it, so here's a little excercise on ray optics for you guys.

All light rays entering a fibre optic cable through it's face side are to be totally internally reflected. What is the minimal refractive index the cable needs to have for this?

1.5?
From my cursory wikipedia reading of everything...
Fkkize
Posts: 2,301
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7/17/2016 3:09:43 PM
Posted: 1 year ago
At 7/17/2016 1:29:51 PM, MagicAintReal wrote:
At 7/14/2016 9:15:25 PM, Fkkize wrote:
Had a physics exam today. Still feel like more of it, so here's a little excercise on ray optics for you guys.

All light rays entering a fibre optic cable through it's face side are to be totally internally reflected. What is the minimal refractive index the cable needs to have for this?

1.5?
From my cursory wikipedia reading of everything...

Sqrt(2), but close :)