lens and mirrors

[Omni]

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hi. i need some helo with the sign convention.
can someone please tell me if this is right:

converge
concave mirror:
object is positive
image is positive
image is inverted
image is real.

convex lens
object is negative
image is positive
image is inverted
image is real
unless within the focal point, its image is oppostie

diverge
convex mirror
object is positive
image is negative
image is upright
image is virtual

concave lens
object is negative
image is negative
image is upright
image is virtual


also, for concave mirror and lens, the image is on the same side of the object, correct?
and please fill in anything i may have missed. i find this to be the most confusing of the ps section. also, i got this info from examkrackers. i was reading through kaplans and they had a few things opposite from what ek said, so that really confused me.

thanks!!

 

[wanderer]

Let me start off by mentioning that the equation q=(p*f)/(p-f) is a lot easier to work with than the 1/f-1/p.
When dealing with enlarged, real or virtual, image depends on both p and f, so some of your rules don't make sense (or I'm misinterpreting). F is positive for converging (convex) lens, and concave mirror. It is negative for diverging lens and convex mirror. + for the image means it is on the same side as objects for mirrors and opposite side for lenses. For converging lens, a real object's image is reduced at greater than 2f, enlarged within 2f, and virtual within 1 f. For a diverging lens, a real object forms a reduced and virtual image everywhere.

 

[wait4me]

Concave Mirror:
Real and inverted
F and I are +
M is -
Image on the same side as human observer

Convex Mirror:
Virtual and upright
F and I are -
M is +
Image on opposite side of human observer

Concave Lens
Virtual and upright
F and I are -
M is +
Image on opposite side of human observer

Convex Lens
Real and inverted
F and I are +
M is -
Image on the same side as human observer

What I get confused about is when they tell us to move the focal point (behind or in front of) somewhere. Do we need to know how to draw the diagrams? Any advice to solving these problems? I remember seeing a problem like that somewhere but i cant find it now

 

[pastryman]

i thought object is always positive...

 

[wanderer]

i thought object is always positive...

For a single lens/mirror system it is. Not so for a more complex system.

 

[pastryman]

Yah but the OP did not state that in his list. I think he was just considering single lens/mirror systems.

 

[clc8503]

Concave Mirror:
Real and inverted
F and I are +
M is -
Image on the same side as human observer

Convex Mirror:
Virtual and upright
F and I are -
M is +
Image on opposite side of human observer

Concave Lens
Virtual and upright
F and I are -
M is +
Image on opposite side of human observer

Convex Lens
Real and inverted
F and I are +
M is -
Image on the same side as human observer

What I get confused about is when they tell us to move the focal point (behind or in front of) somewhere. Do we need to know how to draw the diagrams? Any advice to solving these problems? I remember seeing a problem like that somewhere but i cant find it now

Good Stuff! The only thing thats lacking are the different variables for focal point position in Concave Mirrors.

 

[minutemen11]

are double lens/mirrors systems in the scope for the mcat?? i hope not..

 

[minutemen11]

anyone??

 

[wanderer]

are double lens/mirrors systems in the scope for the mcat?? i hope not..

I don't see why not. Corrective lenses for example can be asked in the MCAT, and are always dual lens, although those questions are usually qualitative, not quantitative. 2 lens systems aren't hard so you should try to learn them.

 

[shaggybill]

http://www.freelance-teacher.com/physics_optics.pdf

Memorize the table at the top. It's pretty useful.