All Questions
Tagged with refraction lenses
135
questions
49
votes
5
answers
13k
views
If a lens focuses all incoming light to a point, how do we get 2D images?
How do lenses produce 2-dimensional images, if a lens bends all incoming rays of light to intersect at the focal point? Shouldn't this produce a single dot of light on a screen placed at the focal ...
- 601
44
votes
4
answers
277k
views
Virtual vs Real image
I'm doing magnification and lens in class currently, and I really don't get why virtual and real images are called what they are.
A virtual image occurs the object is less than the focal length of ...
- 6,927
18
votes
2
answers
2k
views
Why are the edges of the shadow so bright?
Today I noticed something while playing with my specs (having diverging lenses).
Have a look at it :
This is the shadow of my specs on the wall in sunlight. The region of the lens appears darker and ...
- 8,230
11
votes
2
answers
5k
views
Why do convex lenses not disperse light like prisms, given that entry and exit points aren't parallel?
I understand that light entering a parallel block of glass at a non-90 degree angle will cause dispersion of colours within the block but that these will be refracted by the same degree upon exit so ...
- 121
10
votes
2
answers
36k
views
Difference between convexo-concave and concavo-convex lenses?
What is the difference between concavo-convex and convexo-concave lenses? We dont say convexo-plane for plano-convex. Does that mean concavo-convex and convexo-concave are essentially the same?
- 619
5
votes
3
answers
2k
views
Why do different colors appear to move at different rates when I shift my head while wearing eyeglasses?
I have significant nearsightedness (and some astigmatism), but see just fine with eyeglasses. One phenomenon I've noticed is that when I shift my head side to side or up and down while keeping my ...
- 181
5
votes
3
answers
1k
views
Why do lens (convex) not introduce any path difference to light incident on it?
My understanding is that the top rays spend less time inside the lens where the speed of light is slow and the middle rays spend more time inside the lens so the time is kind of compensated . But I'm ...
- 153
5
votes
1
answer
34k
views
How to determine the radius of curvature of a convex lens?
Suppose there is an equi-convex lens made of glass which has a focal length ($f$) of 30cm. Then, can we not say that the radius of curvature, $R$ of the lens is twice the focal length, i.e. $R = 60cm$?...
- 185
5
votes
3
answers
614
views
Light hitting a GRIN (Gradient-index) lens at the optical angle
In the image below, rays of light are hitting the GRIN (Gradient-index) lens at the optical angle and then converge towards the optical axis. Why do they do this? The refractive index is only a ...
- 53
5
votes
0
answers
7k
views
What is Curvature of eye lens?
I wanted to know what do we mean by "curvature of eye lens", is it the reciprocal of $r$ i.e $c=1/r$ or is it synonymous to radius of curvature of the eye lens. Moreover how does aperture relate to ...
- 159
4
votes
2
answers
4k
views
Arrow that changes direction home experiment
I saw this cool optical effect in a experiment on Youtube:
https://www.youtube.com/watch?v=G303o8pJzls
Could anyone explain to me why the arrow points in the opposite direction?
I have read ...
- 55
4
votes
4
answers
1k
views
What is the angle of a ray passing through a thin lens?
Let's say I have a thin lens model of an optical system. When I have a ray that is parallel to the optical axis, the situation is quite standard - the ray refracts and passes the focal point f (see my ...
- 63
4
votes
5
answers
6k
views
Why do we see a blurred image when the screen is not placed at the position where the image is formed by a convex lens?
Regarding the proposed duplicate:
Why does the image lose its clarity when it is formed in front of the retina?
Does the above question answer mine? Short answer: No
Long answer:
Thank you for sharing ...
- 5,306
4
votes
1
answer
865
views
Deep confusion with conventions and signs in geometric optics
This is an equation given in my book.
The question is why have they used a negative sign on the LHS?
Now, if you try to derive the mirror equation with simple geometry, you get
1/v +1/u =1/f . I ...
- 1,770
3
votes
4
answers
5k
views
