Light and optics questions

[premedgeek]

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I am always having trouble with what kind of image does convering/diverging lens/mirror forms?

Can anyone help me out? Kaplan book is not very good at explaning this.

Diverging lens = always virtual and upright?

Converging lens = real and virtual depending on distance

diverging mirror = always virtual?

converging mirror = real or virtual?

 

[DieselPetrolGrl]

all i can remember honestly is "diveeerging are dimmminished upright and virtual" so i believe your right on that one.



.. i go from there and do multi guess 🙁

 

[silkworm]

EK has a great system for this. If you don't want to spend the money, go to the book store and copy down that one page.

In a nutshell:

Concave Mirrors and Converging Lenses: Images are Real, Inverted, Positive, EXCEPT when the object is placed within the focal length, in which case the images are Virtual, Negative and Upright.

Convex Mirrors and Diverging Lenses: Images are always Virtual, Negative, Upright.

I am always having trouble with what kind of image does convering/diverging lens/mirror forms?

Can anyone help me out? Kaplan book is not very good at explaning this.

Diverging lens = always virtual and upright?

Converging lens = real and virtual depending on distance

diverging mirror = always virtual?

converging mirror = real or virtual?

 

[premedgeek]

EK has a great system for this. If you don't want to spend the money, go to the book store and copy down that one page.

In a nutshell:

Concave Mirrors and Converging Lenses: Images are Real, Inverted, Positive, EXCEPT when the object is placed within the focal length, in which case the images are Virtual, Negative and Upright.

Convex Mirrors and Diverging Lenses: Images are always Virtual, Negative, Upright.

Are you using EK books in addition to Kaplan? If so how much better/worse they are?

 

[acepoint]

agreed...the EK system was great...its really easy to remember and apply. I'd just go find that, as hte pictures really help.

 

[DieselPetrolGrl]

EK has a great system for this. If you don't want to spend the money, go to the book store and copy down that one page.

In a nutshell:

Concave Mirrors and Converging Lenses: Images are Real, Inverted, Positive, EXCEPT when the object is placed within the focal length, in which case the images are Virtual, Negative and Upright.

Convex Mirrors and Diverging Lenses: Images are always Virtual, Negative, Upright.

Thank you - what a nice post! I feel very silly asking this but by negative do you mean that the image magnification is negative as in diminshed(-) vs magnified(+)?

Sorry i know i should assume thats what you mean but...uh uh...sometimes i miss big pictures and i am afraid i am so weak at optics. Thank you!

 

[silkworm]

I like them. It's very colorful, literally and figuratively. I don't mind the Kaplan books, but I rather study with the EKs. But EKs doesn't cover quite as much material as Kaplan.

Are you using EK books in addition to Kaplan? If so how much better/worse they are?

 

[silkworm]

Thank you - what a nice post! I feel very silly asking this but by negative do you mean that the image magnification is negative as in diminshed(-) vs magnified(+)?

Sorry i know i should assume thats what you mean but...uh uh...sometimes i miss big pictures and i am afraid i am so weak at optics. Thank you!

No, (+) means in the same side as the Eye, (-) means in the opposite side from the Eye.

At least I think that's all they mean. If someone knows better please correct me.

 

[premedgeek]

No, (+) means in the same side as the Eye, (-) means in the opposite side from the Eye.

At least I think that's all they mean. If someone knows better please correct me.

Sorry to bother you again, but is it work buying EK Comprehensive review if you have Kaplan books down cold?

I am contemplating on getting EK books and reading them over once before MCAT. I jsut want to make sure i am not missing any concepts from Kaplan book.

 

[silkworm]

If you know the material already, then I don't think it's worth it.

 

[GBFKicks]

I am always having trouble with what kind of image does convering/diverging lens/mirror forms?

Can anyone help me out? Kaplan book is not very good at explaning this.

Diverging lens = always virtual and upright?

Converging lens = real and virtual depending on distance

diverging mirror = always virtual?

converging mirror = real or virtual?

I just did them enough where I have a pretty good idea as to what will happen in each case. I would recommend that you just draw them out a few times (shouldn't take very long)--using the three lines. If you don't know them, then I can explain it further. The only ones that are tricky after that are the ones in which the object is on the focal point. These optics problems should be easy points if you get it down....
I think it's good to be able to draw them out anyway in case you get them confused during the test. And, they are fast and easy to draw. I'm pretty sure everyone learned how to draw them in physics, but if not, then go ahead and post or PM and someone can explain it.

 

[premedgeek]

I just did them enough where I have a pretty good idea as to what will happen in each case. I would recommend that you just draw them out a few times (shouldn't take very long)--using the three lines. If you don't know them, then I can explain it further. The only ones that are tricky after that are the ones in which the object is on the focal point. These optics problems should be easy points if you get it down....
I think it's good to be able to draw them out anyway in case you get them confused during the test. And, they are fast and easy to draw. I'm pretty sure everyone learned how to draw them in physics, but if not, then go ahead and post or PM and someone can explain it.

Can you explain the deal with three line please?

 

[MsEvolution]

Yes, please do explain...

 

[GBFKicks]

Can you explain the deal with three line please?

Let me see if I can find a diagram online and I can go from there.... it's easier to just see it... otherwise I'll just plain try to explain it...

Actually, EK has the same method... I looked there before looking online... it's on page 149 of the 5th edition. I'll check back in when I find a link to a website.

 

[GBFKicks]

Here is a website that I've found... If it tells you that you need chinese characters just click cancel.... it worked when I did it.
http://www.phy.ntnu.edu.tw/java/Lens/lens_e.html

Make sure you try it out with the image both inside and outside of the focus point, because the image changes.

In general, here is how the lines work:
First line- from the top of the object straight to the lens/mirror and bends to the focal point (either on same side or opposite side of lens depending on type of lens)
Second line- from top of object to the middle of lens/mirror. This either either continues past the lens or comes back at the same angle it went in depending on type of lens/mirror
Third line- from top of object through the focal point and to the lens/mirror. This line then goes straight out.

The place where the lines meet is the head of the image. If it is a continuation of an actual light ray that made the image, it is real.

Look at the link-- it has a great program on it where you can change the lens/mirror type and change the position of the image. Make sure to move the object inside and outside of the focal point and notice how the rays form the image. It becomes extremely easy that way. If you have any questions, I can go into greater depth...

 

[willthatsall]

That web site kicks ass. Nice work. 👍

 

[GBFKicks]

Can you explain the deal with three line please?

Does that help you guys? If you want, I can go into more detal. It might not be completely clear how those lines work when the object is inside the focal point. Anyway, PM me if you want me to explain it to you.. I think it's really useful and once you get it, then it's really fast and easy.

 

[DieselPetrolGrl]

i Loved ur link ..cleared it all up for me! thanks ...btw i dont use ray diagrams...i find they take me too long - think its a must for mcat? i have the rules memeorized..hopefully i can bump into some practice Qs on the kaplan mcat 1-5 to check me on them ..willthatsall..have u seen them on any particular one? ( u are ahead of me i have taken fl1 and 2 and still dropping esp in verbals)

 

[willthatsall]

i Loved ur link ..cleared it all up for me! thanks ...btw i dont use ray diagrams...i find they take me too long - think its a must for mcat? i have the rules memeorized..hopefully i can bump into some practice Qs on the kaplan mcat 1-5 to check me on them ..willthatsall..have u seen them on any particular one? ( u are ahead of me i have taken fl1 and 2 and still dropping esp in verbals)

Haha, now that you mention it, there is a pretty killer optics question on FL 3. I don't know, maybe you won't think it is that bad, but it's kinda weird how they ask it. It's just a discrete though, nothing too important. I got it right on a semi-guess. I need to get this stuff down better. Did you say your scores dropped from FL 1 to FL 2? I thought 2 was easier. 😕

 

[GBFKicks]

i Loved ur link ..cleared it all up for me! thanks ...btw i dont use ray diagrams...i find they take me too long - think its a must for mcat? i have the rules memeorized..hopefully i can bump into some practice Qs on the kaplan mcat 1-5 to check me on them ..willthatsall..have u seen them on any particular one? ( u are ahead of me i have taken fl1 and 2 and still dropping esp in verbals)

Yeah, I'm with you... at this point I rarely use them, but they were how I learned optics/lenses/mirrors. I just think they are good if you don't understand them or if you get confused or forget some of the rules. It's good to know they for the MCAT because they are fairly simple.

 

[premedgeek]

Does that help you guys? If you want, I can go into more detal. It might not be completely clear how those lines work when the object is inside the focal point. Anyway, PM me if you want me to explain it to you.. I think it's really useful and once you get it, then it's really fast and easy.

Thanks a lot. This clears up most of my problems.