lens and mirrors

[sangria1986]

Lens- if image is opposite to light source, image is positive

focal point of converging lens is positive because its on opposite side

converging lens create real images (or maybe even both)

Both real and virtual images by lenses are visible to eye

focal point of diverging lens is on same side so it is negative

diverging lens create virtual images on same side as object

concave mirrors have positive focal points and can create virtual or real images. real images are on same side as light source, virtual image is behind. concave focal point is on same side

convex mirrors always create virtual and upright images and always have negative focal point because its on opposite side.

Are these correct?

I didnt memorize these but based it off memorizing the direction of light rays (which is pretty common sense considering the curvatures of the lenses) But I want to make sure my analysis is correct.

what do rays diverging from a POINT do once they hit a divirging lense?

parallel rays into a diverging lens reflect back to a converging point (its negative focal point) but behind the lens they are divirging.

parallel rays going into a converging lens converge at the other end at its positive focal point

is this all correct?

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[SoonerLuke]

the thing i memorized is....

convex mirror, diverging lens= negative, virtual, upright images

concave mirror, converging lens= positive, real, inverted images

This holds true as long as you use common sense and think of objects being "in front" of mirrors and "behind" lenses.

 

[super6]

the thing i memorized is....

convex mirror, diverging lens= negative, virtual, upright images

concave mirror, converging lens= positive, real, inverted images

This holds true as long as you use common sense and think of objects being "in front" of mirrors and "behind" lenses.

I thought that if you have a converging mirror with an object inside the focal point, the image will be virtual upright and enlarged

 

[SoonerLuke]

I thought that if you have a converging mirror with an object inside the focal point, the image will be virtual upright and enlarged

That's correct, I forgot to add that exception. For a concave mirror or converging lens, if the object is within the focal distance, then the image with be negative, virtual, and upright.

 

[pmahesh107]

The way I approach mirror/lens problem is this and I have yet to encounter a scenario where it doesn't work. For all converging lenses and mirrors (concave for mirror, convex for lense), f is positive. For all diverging (convex for mirror, concave for lense), f is negative.

After that I just use the equation 1/o + 1/i = 1/f, where f is the focal length, o is the distance of the object from the lense/mirror, and i is the image distance from the lense or mirror.

i is what determines what the image is. If i is positive, the image is real and inverted. If i is negative, the image is virtual and upright.

The only other thing is magnification, just use m = -i/o.

 

[Chocolatebear89]

I think according TPR, all virtual images are upright, and all real images are inverted.

But couldn't Virutal images also be inverted?