Basically what the question says. Convex lenses form images that are real and inverted and obtained on a screen unless the object is placed extremely close to the lens. So why am I able to see an inverted image of the object needle through the lens without any screen? The aim of the practical experiment is to find the focal length of the convex lens provided to us using an optical bench.
Why can I see inverted image of object needle on top of image needle using convex lens on optical bench
experimental-physicslensesopticsvisible-light
Related Solutions
If you get in line with the light travelling through the lens at a location beyond the real image point and look back toward the lens, you can see the image "floating" in the air. If you get far off-axis, you won't see it. The light from the image must travel (somehow) to your eyes. It takes some practice to get your eyes to focus on the image rather that the lens or other surroundings, but it can be done. Mirrors work very nicely, too, to let you see images from off-axis positions.
If the concave lens was not there and the object was at a distance greater that its focal length the convex lens would form a real image.
Introducing a concave lens results in the incoming rays from the convex lens being refracted as shown in the diagram above.
The refracted rays are still convergent and so form an image $I$ at a distance $q_2$, your $d_v$, from the the concave lens.
After passing through the convex lens where the rays would have met is at a distance $p_2$, your $d_R$, from the concave lens and that can be thought of as a virtual object for the concave lens.
Related Question
- [Physics] Is real image formed by a single optical element always inverted and virtual image always erect
- [Physics] 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
- Why is the size of image increasing as observer moves away from lens
Best Answer
When talking about a screen in optics, it is often referred to as the projection of the object after going through the lens. It is better to imagine it as I will describe now:
Suppose you have your lens in the middle of the setup and you were to have on one side a projector and on the other side a screen. The object coming out from the projector would then go through the lens and be flipped, afterwards it would travel till it reaches your screen and you would notice it is flipped. Here you can see the actual image of the object flipped because you are actually projecting the object itself with the projector to a screen.
In your scenario, you are the screen that is observing the light coming from the object which is then going through the lens, thus you/the retina sees the object inverted.