Sunday 19 August 2018

optics - How is it possible that a converging lens can form a virtual image if its function is to make the light converges?


If the function of a converging lens is to do the light converge, how it can form a virtual image, which as far as I know is formed when the light diverges ?


I have another question, that may seems dumb for you, but I really have problems trying to understand real and virtual images, maybe because I´m taking the optics lab when I haven't taken the corresponding theoretical class:


The image form by the objetive of a rudimentary mycroscop and a refractor telescope needs to be real in order to the ocular can amplify it ? If I set the object whithin the focal lenght of the objective, a virtual image is formed, can the ocular formed and image of this virtual image?



Answer




which as far as I know is formed when the light diverges?




The lens tries its best and makes the light less divergent but is not powerful enough to make it convergent.


enter image description here


What you are asking for is a virtual intermediate image to the left of the first lens light from which is focussed a second lens.
Here is a possible arrangement of lenses where the first lens produces a virtual image and the final image is at infinity.


enter image description here


This is the ray diagram for a Galilean telescope which is much shorter than a conventional refracting telescope where the intermediate image is never formed and is said to be a virtual object for the second lens..


enter image description here


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