What is Real image: Definition and 19 Discussions

In optics, an image is defined as the collection of focus points of light rays coming from an object. A real image is the collection of focus points actually made by converging rays, while a virtual image is the collection of focus points made by extensions of diverging rays. In other words, it is an image which is located in the plane of convergence for the light rays that originate from a given object. Examples of real images include an image on a cinema screen (the source being the projector, and the screen plays as a diffusely reflecting surface so the image formed on the screen plays as an object to be imaged by human eyes), the image produced on a detector in the rear of a camera, and the image produced on an eyeball retina (the camera and eye focus light through an internal convex lens).
In ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines; perceived or extrapolated rays of light are represented by dashed lines. A real image occurs where rays converge, whereas a virtual image occurs where rays only appear to diverge.
Real images can be produced by concave mirrors and converging lenses, only if the object is placed further away from the mirror/lens than the focal point, and this real image is inverted. As the object approaches the focal point the image approaches infinity, and when the object passes the focal point the image becomes virtual and is not inverted (upright image). The distance is not the same as from the object to the lenses.
Real images may also be inspected by a second lens or lens system. This is the mechanism used by telescopes, binoculars and light microscopes. The objective lens gathers the light from the object and projects a real image within the structure of the optical instrument. A second lens or system of lenses, the eyepiece, then projects a second real image onto the retina of the eye.

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  1. N

    Virtual and real image with concave mirror at 45 degrees

    I have a spherical concave mirror with focal length of 65cm, radius of curvature of 130cm. I hold the mirror close to the eye at approximate 45 degrees and I reflect an object below it as shown in the image. The distance between the object and the mirror is 90cm, that is more than the focal...
  2. P

    A Real image of a sawtooth standing wave in a musical string?

    Hi there I am teaching resonance and standing waves in stringed instruments at the moment at high school. The theory states that a number of standing waves simultaneously (harmonics) exist in a naturally vibrating musical string, but with varying amplitudes, the 1 st harmonic being loudest...
  3. navneet9431

    B Can we get a real image of virtual objects?

    Is it possible to get a real image of virtual objects, If so please explain with examples and some real life situations? Look at my assertion "rays will not pass through virtual objects so how it can form real image", is this possible, please help.
  4. navneet9431

    B Where will the image be formed?

    Suppose light rays from an object fall perpendicular to the surface of the plane mirror. Will the image be formed at +infinity(a virtual image) or -infinity(a real image)? I will be thankful for help!
  5. Krushnaraj Pandya

    Are Real Images Always Inverted and Virtual Always Erect in Ray Optics?

    Homework Statement My question is, are real images always inverted and virtual always erect? Homework Equations 1/v+1/u=1/f for mirrors and 1/v-1/u=1/f for lenses The Attempt at a Solution Consider a concave lens, with object at -x. the condition for a virtual image is v<0; i.e on the same...
  6. F

    Real image appears in front of the mirror?

    Is there a simple way to determine or prove this? Real images are always inverted, and unlike virtual images can be projected onto a screen (I'm not even sure what this means to be honest). If I look at the back end of a spoon (convex mirror), the image is always upright and therefore virtual...
  7. javier meraz

    B Angle of vision for a real image

    Hi there, i want to know as much as possible about this situation. I want to know the angles of vision for a real image, where can one see the image, the location of our eye to see it. Which factors determine this angle Thank you so much :D I hope this isn't a dumb question, thanks.
  8. P

    Image of a virtual object by a plane mirror

    A plane mirror forms a virtual image of a real object placed in front of it and a real image of a virtual object placed in front of it. I can't picture the second case. Please show me a ray diagram showing real image formation by a plane mirror or just explain the case of real image formation by...
  9. Max Matiauda

    Image formed from object at focal point of concave mirror

    The question posed: "An object is located to the right of a mirror that in concave in its [the object's] direction. If the object sits on the focal point of the mirror, what answer best describes the image formed?" Our class is united in the notion that as the rays would be parallel...
  10. S

    Can a real image be formed by a virtual image?

    That is, take the virtual image as the object for a second lens?
  11. S

    Why do our eyes need to be far from the lens to view a real image?

    I do understand that we don't need a screen to view a real image, but why our eyes need to be far away from the lens than the image? Why can't we be exactly where the image would normally appear if we had a screen? Moreover, the image there is sharp because the rays converge exactly at that...
  12. A

    Optics: Can a magnified real image be larger than the lens diameter?

    Hi all, This is probably a silly questions, but I want to be sure :). I'm wondering if a real image, created by a convex lens, can appear larger than the lens diameter itself. As an example, I'm thinking about the following: - I have a an object of height h_0=7.76" (display size of...
  13. T

    Real Image Optics: Selecting Correct Answer

    Homework Statement Doing some practice problems to prepare for upcoming exam and ran across this: A real image is a. One in which light does not pass through the image point but appears to diverge from that point b. One for which the magnification equal 1 c. An excellent image d. An...
  14. P

    What's the difference between a virtual and a real image

    I cannot seem to get the concept of real and virtual image. This is my understanding. If the light beams go to the reflecting surface(concave or convex mirror) then an image will be form assuming the reflecting beams meat at a point. If the image appears to be in front of the mirror(s' is...
  15. H

    Do we need a screen to view a real image?

    So, the question I ask is simple : " Is a screen necessary to view a real image?" For example, when I view my image at the 'concave mirror' side of a spoon, a real image is visible. Now, according to my book the image location should be between Centre and Focus. So, is the image actually...
  16. O

    Real image from concave mirror

    "real" image from concave mirror Ok so in we are currently doing mirrors and reflections in physics and from what I learned there are 2 types of images: real and virtual. I know that a virtual image is what you see INSIDE the mirror; but what does a real image looks like? I can't find anything...
  17. P

    Real Image in a Concave Mirror: Virtual Object Analysis

    how can we say that the image formed by a concave mirror is always real if object is virtual? please help
  18. P

    Literally seeing a real image?

    Normally we see a virtue image after light from the object reflects off a mirror. We then trace back to behind the mirror to a point where the virtue image came from. A real image is seen when light from the object projecting the image reflects off a screen or mirror and we see it with our...
  19. E

    The minimum distance between an object and it's real image

    Maybe it's just late, but I'm having an extremely difficult time proving that the minimum distance between an object and it's real image (geometric optics, thin lense equation) is 4f. I can see that it is true, however I'm unsure how to go about proving it mathematically.