Help! Light and Optics

[Clemson Doc]

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If you guys would help me out with light and optics stuff, I will be most appreciative. I feel like I ride the light and optics short bus. I know it's not usually that important on the MCAT, aside from a discrete question or something, but I would like to know as much as possible just in case.

I understand Snell's law, angles of incidence, reflection, and refraction, n=c/v, and all that just fine. My main problems are with mirrors and lenses. Here is what I know (or at least think I know...ha ha):

concave mirrors are converging
convex mirrors are diverging
convex lenses are converging
concave lenses are diverging

(1/f) = (1/i) + (1/o)
m = -(i/o)

positive images are always real and inverted
negative images are always virtual and upright

Now, drawing ray diagrams and knowing what kind of image exists when it's within two focal lengths of a diverging lens and other similar questions is a mystery to me. If anyone can help me out with this, I would greatly appreciate it. Thanks in advance!

 

[AxlxA]

Just know convex mirrors/lenses has -f. it's all about manipulating that 1/f = 1/i + 1/o equation. u seem to know as much as me about it.

so for the image 2 focal length thing, stick it into the formula. 1/f = 1/i + 1/2f, 1/i has to be positive inorder to satisfy the equation, hence real image.

btw POwer of a lense = 1/f, units: diopters (m^-1) meters not CM

 

[Pembleton]

I'd also suggest not wasting too much time drawing ray diagrams. Trust the formulas and the conventions for your answers.

 

[Dr. N]

If you guys would help me out with light and optics stuff, I will be most appreciative. I feel like I ride the light and optics short bus. I know it's not usually that important on the MCAT, aside from a discrete question or something, but I would like to know as much as possible just in case.

I understand Snell's law, angles of incidence, reflection, and refraction, n=c/v, and all that just fine. My main problems are with mirrors and lenses. Here is what I know (or at least think I know...ha ha):

concave mirrors are converging
convex mirrors are diverging
convex lenses are converging
concave lenses are diverging

(1/f) = (1/i) + (1/o)
m = -(i/o)

positive images are always real and inverted
negative images are always virtual and upright

Now, drawing ray diagrams and knowing what kind of image exists when it's within two focal lengths of a diverging lens and other similar questions is a mystery to me. If anyone can help me out with this, I would greatly appreciate it. Thanks in advance!

I really liked the optics diagram they have in EK physics book. it is simple and understandable.

concave mirrow - ) -looks like cave and has focal point sitting in the cave-- will always make real positive (SAME side as your eyes) inverted image

convex mirrow - (-- inverted cave and again has focal point siting inside of the cave and therefore it is negative because it is on the opposite side from your eyes -- will always make vitual (opposide side from your eyes) upright image

Converging (convex) lens - () - has focal point on the same side as your eyes and will produce positive real inveted image

Diverging (concave - two caves together) )( -- has focal point on the opposite side of the lens from your eyes and it is negative, makes negative virtual upright image.

hope this helps

 

[BigLazy]

The only mirror question that are gonna ask will be like "describe the image if a person is standing in front of the focal point". At least I hope cuz that's the only thing I know about lens and mirrors.

 

[AxlxA]

You wouldn';t see anything if u'r standing at focal point if it's a converging mirror right? same goes for the converging lense?

1/f = 1/i + 1/o, 1/f = 1/i + 1/f, 1/i = 0, i-> oo

 

[CH3CH2OH]

I really liked the optics diagram they have in EK physics book. it is simple and understandable.

concave mirrow - ) -looks like cave and has focal point sitting in the cave-- will always make real positive (SAME side as your eyes) inverted image

convex mirrow - (-- inverted cave and again has focal point siting inside of the cave and therefore it is negative because it is on the opposite side from your eyes -- will always make vitual (opposide side from your eyes) upright image

Converging (convex) lens - () - has focal point on the same side as your eyes and will produce positive real inveted image

Diverging (concave - two caves together) )( -- has focal point on the opposite side of the lens from your eyes and it is negative, makes negative virtual upright image.

hope this helps

also from EK:
you can use the mnemonic: "I (eye) am positive that real is inverted"
images that are formed on the side of the eye (the + side) are always positive, real, and inverted. concave mirrors and converging (convex) lenses form these images (except when the object is w/in the focal distance. then they form negative, virtual and upright images)
images that are formed on the opposite side are negative, virtual and upright. those are formed by convex mirrors and diverging (concave) lenses.

 

[mesoderm]

also from EK:
you can use the mnemonic: "I (eye) am positive that real is inverted"
images that are formed on the side of the eye (the + side) are always positive, real, and inverted. concave mirrors and converging (convex) lenses form these images (except when the object is w/in the focal distance. then they form negative, virtual and upright images)
images that are formed on the opposite side are negative, virtual and upright. those are formed by convex mirrors and diverging (concave) lenses.

Thanks! I needed this. Also, I found this one: "DEV : Diverging, Erect and Virtual images", and the "Seer sees CIR: Converging, Inverted and Real images".

 

[GBFKicks]

If you guys would help me out with light and optics stuff, I will be most appreciative. I feel like I ride the light and optics short bus. I know it's not usually that important on the MCAT, aside from a discrete question or something, but I would like to know as much as possible just in case.

I understand Snell's law, angles of incidence, reflection, and refraction, n=c/v, and all that just fine. My main problems are with mirrors and lenses. Here is what I know (or at least think I know...ha ha):

concave mirrors are converging
convex mirrors are diverging
convex lenses are converging
concave lenses are diverging

(1/f) = (1/i) + (1/o)
m = -(i/o)

positive images are always real and inverted
negative images are always virtual and upright

Now, drawing ray diagrams and knowing what kind of image exists when it's within two focal lengths of a diverging lens and other similar questions is a mystery to me. If anyone can help me out with this, I would greatly appreciate it. Thanks in advance!

Here is a program that helps out with the lines. It's a java program on the website, so you don't have to download it at all. It lets you play around with object placement, lens type and etc...
http://www.phy.ntnu.edu.tw/java/Lens/lens_e.html

 

[willthatsall]

Here is a program that helps out with the lines. It's a java program on the website, so you don't have to download it at all. It lets you play around with object placement, lens type and etc...
http://www.phy.ntnu.edu.tw/java/Lens/lens_e.html

Yeah this is the website I was telling someone about yesterday but I couldn't remember who posted it originally. It's awesome though.

 

[Monkey12]

what do you guys know about radius of curvature, is it just R/2=f?