Difference between revisions of Optics related math
→The thin lens equation: mention converging lens with s < f. Could do with some more pictures, really... |
m →Infinity: minor rewording, to paint a picture of the object moving towards the lens continuously, rather than just jumping straight from infinity to the focus. |
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The term '''object at infinity''' is often used. When <math>s=\infty</math> is substituted into the thin lens equation, that term vanishes, so that the focal length is then just the image location. For any sufficiently large object distance, the contribution from the reciprocal becomes negligible. | The term '''object at infinity''' is often used. When <math>s=\infty</math> is substituted into the thin lens equation, that term vanishes, so that the focal length is then just the image location. For any sufficiently large object distance, the contribution from the reciprocal becomes negligible. | ||
As the object approaches the lens, the outgoing rays converge less and less, until the object reaches the focus of the lens (<math>s=f</math>), and the transmitted light is parallel - we say it "focuses at <math>s'=\infty</math>", which means it never comes together into a focus. | |||
===Virtual image=== | ===Virtual image=== | ||