What will be the path of ray passing through the first focal length of a biconcave thin lens kept in air?

I know that a ray passing through focus or appearing to pass through focus of a thin lens becomes parallel to the principal axis. But in this case I cannot see how? enter image description here


The ray passing from the focus, after the lens overlaps with the one that starts from the tip of the virtual image, see the image. (Basically that ray is not a "special" one).

enter image description here

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  • $\begingroup$ But shouldn't a ray passing through the focus be parallel to the principal axis of the lens? $\endgroup$ – Utkarsh Barsaiyan Feb 19 '16 at 11:30
  • $\begingroup$ on a positive lens only. $\endgroup$ – scrx2 Feb 19 '16 at 11:35
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    $\begingroup$ try this software to play with optics $\endgroup$ – scrx2 Feb 19 '16 at 11:37
  • $\begingroup$ @Utkarsh Barsaiyan do you find the answer acceptable? if yes, consider accepting it $\endgroup$ – scrx2 Mar 17 '16 at 21:02

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