magnification lens/mirros

[nhernandez4]

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Besides the magnification equations does any one have any general guidelines for determining if something has been magnified or not for converging and diverging lens and mirrors..

 

[loveoforganic]

I believe, but am not 100%, that diverging always shrinks and converging magnifies only when the object is within the focal length.

 

[Naijaba]

Check out the ExamKracker's Physics book. It has four pages devoted to simplifying the memorization of lens concepts. It takes a good couple of hours to fully digest, but it is solid knowledge.

 

[G1SG2]

I believe, but am not 100%, that diverging always shrinks and converging magnifies only when the object is within the focal length.

I'm not sure about that. I know that the converging lens produces an upright, virtual image when the object is within the focal lens.

 

[capn jazz]

I'm not sure about that. I know that the converging lens produces an upright, virtual image when the object is within the focal lens.

Yea, the image produced is behind the object and bigger.

Start off with an object outside the focal length for a converging lens. The image is Real and Inverted. As you move the object closer, the image gets bigger and bigger, while remaining real and inverted. Once you pass the focal length, the object immediately switches to an Upright/Virtual object. The closer you get to the lens within the focal length, the bigger the image gets (still behind the object)

Proof is here:

http://cantor.deas.harvard.edu:8182...42748a87c48c1f4d24f43c2008587d&lectureID=4964

Scroll halfway down the page for a ray diagram.

And here:
http://www1.union.edu/newmanj/lasers/Geometrical_Optics/Geometrical Optics.htm

 

[wanderer]

I'm not sure about that. I know that the converging lens produces an upright, virtual image when the object is within the focal lens.

take 1/q = 1/f - 1/p and rearrange it to q= p*f / (p-f). If you substitute some number in between f and 2f (say 1.3f) you get q = 1.3f²/(.3f) = 13/3 f. So we see that anything within 2f produces an enlarged image for a converging lens.

 

[G1SG2]

Yea, the image produced is behind the object and bigger.

Start off with an object outside the focal length for a converging lens. The image is Real and Inverted. As you move the object closer, the image gets bigger and bigger, while remaining real and inverted. Once you pass the focal length, the object immediately switches to an Upright/Virtual object. The closer you get to the lens within the focal length, the bigger the image gets (still behind the object)

Proof is here:

http://cantor.deas.harvard.edu:8182...42748a87c48c1f4d24f43c2008587d&lectureID=4964

Scroll halfway down the page for a ray diagram.

And here:
http://www1.union.edu/newmanj/lasers/Geometrical_Optics/Geometrical Optics.htm

take 1/q = 1/f - 1/p and rearrange it to q= p*f / (p-f). If you substitute some number in between f and 2f (say 1.3f) you get q = 1.3f²/(.3f) = 13/3 f. So we see that anything less within 2f produces an enlarged image.

No I thought the poster meant that there is magnification only when the object falls within the focal length. There is also magnification with the object is NOT within the focal length, right?

 

[wanderer]

No I thought the poster meant that there is magnification only when the object falls within the focal length. There is also magnification with the object is NOT within the focal length, right?

Yea I was agreeing with you....

 

[G1SG2]

Yea I was agreeing with you....

Haha yeah oops, I quoted you by accident 😛

 

[capn jazz]

Yea, sorry, I was agreeing with you as well.

 

[G1SG2]

Yea, sorry, I was agreeing with you as well.

Oops x 2. Okay, but a diverging lens won't magnify, regardless of whether the object is within or behind the "focal point", right?

 

[wanderer]

😕

I'm just confused now.

 

[wanderer]

Oops x 2. Okay, but a diverging lens won't magnify, regardless of whether the object is within or behind the "focal point", right?

Correct. Again take q=p*f / (p-f)
Since f is negative the denominator is always greater than f so that magnitude of q = p * f / (Xf) where X is some number greater than 1. So q must always be less than f. If you have a virtual object this won't work though.