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Second focal point of a concave lens

by Fiona Rozario
Tags: concave, focal, lens, point
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Fiona Rozario
#1
Jun12-14, 02:50 AM
P: 8
Why is the focal point to the left of a concave lens called the second focal point? Isn't it just a matter of the name? So can't the focal point on the left of the lens be called F1 instead of F2?
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adjacent
#2
Jun12-14, 03:43 AM
PF Gold
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P: 1,496
Why not? Focal point is just a name.It's not even real in concave lenses.
jtbell
#3
Jun12-14, 06:27 AM
Mentor
jtbell's Avatar
P: 11,780
When you have incoming parallel rays, the outgoing rays converge towards or diverge from the first focal point.

When you have outgoing parallel rays, the incoming rays converge towards or diverge from the second focal point.


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