What if the 2nd lens is closer to the 1st lens than the 1st lens' focal length? e.g. if the 2nd convex lens is 2.5 cm away from the 1st convex lens and both have focal lengths of 5 cm?
It's because the second lens treats the first lens' d_i point as it's object. The image made by the first lens is inverted, and the second lens does not "invert it back" because it's m is positive :)
Because the second lens isn't "seeing" the subject, it only sees i1, which is upside down. Lens 2's magnification is positive, so it doesn't flip it again, so it stays inverted.
if di is negative (-6cm from the calculation) shouldn't it be on the same side of the eye based on your explanation? I get that it will be on the left side of the second lens because the focal length is -10 cm, but following your explanation made me little bit confused.
when it comes to image distance, if the number is positive the image is on the same side as the eye (between the lens and the eye) and if the answer is negative then the image on the other side of the lens.
For the first lens if u, f and v all are positive, then all should be on the same side... BUT THEY'RE NOT ON THE SAME SIDE. as for convex lenses the focus is on the other side of the object f and u should have opposite signs!!!!! THAT'S A MISTAKE!!!!!
Hi you explained nicely but 2:43 it u (object distance ) will be negative because according to sign convention of lenses, all distances are taken to be positive when they are in the direction of the incident ray.
at 8:45 in the "Thin lens equation and problem solving" video, David, says " -di = non inverted and +di = inverted; however, in this video at 12:16, he draws the image as inverted, even though he got -di. Why is this? Is this just a "special case" with multiple lenses?
Inverted refers to the object image, in the second lens, the "object" which is Image 1 is already upside down. Since di is negative and M becomes positive its non inverted, aka meaning Image 1 (is not inverted, stays the same as it is which is underneath/inverted). If di was positive, you would invert image 1, inverting an image upside down, would make it right side up.
i ve senn little so far of but in terms of theory they seam correct however the mathemathics are completly wrong i mean please put a disclamer cause it is really bad and it can induce in error
This guy is good. Khan academy needs more people like him.
This video was the best explanation of a multi-lens system I have found thus far.
What a wonderful video! Excellent explanation, I would rate this as A+ standard
For lens 2, How it becomes -6 (di)?
I love Khan Academy! Thank you!
What if the 2nd lens is closer to the 1st lens than the 1st lens' focal length? e.g. if the 2nd convex lens is 2.5 cm away from the 1st convex lens and both have focal lengths of 5 cm?
Would you guys consider doing more complex optics videos specifically covering Gaussian lens systems??
tysm u saved my final exam for tomorrow
Thank you so much Khan academy
In this exercise what gain we got in this composition lens where magnification is reduced to ,2 times?
Is the "object" for the second lens not a "virtual object"? And, should the "Object distance" in that case not be negative?
How did you add those fractions
6:20 on the concave lens that image distance would be positive (sign convention) you may Google and check
you are wrong. whether the image distance is positive or negative is based on your calculations via the lens formula.
@@sme_station5179 he cant be wrong he is Asian
OMG I UNDERSTOOD!!!
Hi theacher, can I use these formuls in this video in any case.
I think the answer is -5 cm not 6
u saved me
how does that adding fractions work? I'm not getting those numbers for Di at all
Mohammad Hussain same here
Find the LCM. between d denominators, then u divide the LCM by the denominators and multiply by numerator.
awesome
How did he get 1/18 for di when 1/12 - 1/36 = - 1/24
Michal Korneev u can't divide denominator directly
Power leans scope Objects ma diamond 💎 (bem of leaser)
on the second lens, since m>0, can you explain to me why it is not upright and why inverted @__@
+gidyawn chew It was obviously a mistake...
It's because the second lens treats the first lens' d_i point as it's object. The image made by the first lens is inverted, and the second lens does not "invert it back" because it's m is positive :)
Because the second lens isn't "seeing" the subject, it only sees i1, which is upside down. Lens 2's magnification is positive, so it doesn't flip it again, so it stays inverted.
nicee
thin_lens_formula:
image.distance = focal_length * object.distance / (object.distance - focal_length);
object.distance = focal_length * image.distance / (image.distance - focal_length);
focal_length = image.distance * object.distance / (image.distance + object.distance);
magnification_formula:
magnification = -image.distance / object.distance;
magnification = image.height / object.height;
total_magnification_formula:
for (i = 1; i < total, ++i)
magnification[0] *= magnification[i];
# License: CC BY-SA 4.0 or later, AGPL V3.0 or later #
if di is negative (-6cm from the calculation) shouldn't it be on the same side of the eye based on your explanation? I get that it will be on the left side of the second lens because the focal length is -10 cm, but following your explanation made me little bit confused.
when it comes to image distance, if the number is positive the image is on the same side as the eye (between the lens and the eye) and if the answer is negative then the image on the other side of the lens.
thank you! life saver
For the first lens if u, f and v all are positive, then all should be on the same side... BUT THEY'RE NOT ON THE SAME SIDE.
as for convex lenses the focus is on the other side of the object f and u should have opposite signs!!!!!
THAT'S A MISTAKE!!!!!
What do if the image distance of convex lens is greater than distance BTW lenses
love you khan academy , you are the best of best , thanks and keep making such aha moment videos😉😉😉
Galileo Galilei I believe used these two lenses for he's telescope.? i wasn't there at the time so i could be wrong.
Hi you explained nicely but 2:43 it u (object distance ) will be negative because according to sign convention of lenses, all distances are taken to be positive when they are in the direction of the incident ray.
the formula he used is different. he used mirror formla
Can you do a 3, 4, 5 lense?
at 8:45 in the "Thin lens equation and problem solving" video, David, says " -di = non inverted and +di = inverted; however, in this video at 12:16, he draws the image as inverted, even though he got -di. Why is this? Is this just a "special case" with multiple lenses?
Inverted refers to the object image, in the second lens, the "object" which is Image 1 is already upside down. Since di is negative and M becomes positive its non inverted, aka meaning Image 1 (is not inverted, stays the same as it is which is underneath/inverted).
If di was positive, you would invert image 1, inverting an image upside down, would make it right side up.
Sign confused
You're the best 😭
NIce.
omg kmn
M should be equals to positive v/u, not negative?? Please correct me if I was wrong...
no it should not be equal to v/u as you take negative v for the equation.
charis teoh yi en it is positive for mirror formula but it is a lens so it will be negative
i ve senn little so far of but in terms of theory they seam correct however the mathemathics are completly wrong i mean please put a disclamer cause it is really bad and it can induce in error
Whats his name??
Magnification does not tell the exact length of the object right?
Thanks, it's very clear and easy to follow along!
How about image created by first lens is behind the second lens?
What screen recording software do you use? I would like to know a good one that allows me to pause recording.
Thank you so much! You are an amazing teacher.
thank you so very much for this explanaiton, it really helps a lot ! (also your voice is really nice to listen to :D)
Thank you so much
Thanks it's really helpful
Excellent lecture ❤️❤️❤️❤️❤️
❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤❤
when u said 'its gonna make an image of an image i laughed so hard . but thanks man aved me
I also freaked out on my last semester test
Which year?