Why do we need a screen to see a real image whereas a virtual image can be seen without a screen?












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We did a physics practical in which I couldn't see the image formed by the convex lens without the screen. But I can see the virtual image formed by the plane mirror without a screen.










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$endgroup$








  • 3




    $begingroup$
    Duplicate You do not need a screen to see a real image.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:05
















3












$begingroup$


We did a physics practical in which I couldn't see the image formed by the convex lens without the screen. But I can see the virtual image formed by the plane mirror without a screen.










share|cite|improve this question











$endgroup$








  • 3




    $begingroup$
    Duplicate You do not need a screen to see a real image.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:05














3












3








3





$begingroup$


We did a physics practical in which I couldn't see the image formed by the convex lens without the screen. But I can see the virtual image formed by the plane mirror without a screen.










share|cite|improve this question











$endgroup$




We did a physics practical in which I couldn't see the image formed by the convex lens without the screen. But I can see the virtual image formed by the plane mirror without a screen.







optics






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share|cite|improve this question













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share|cite|improve this question








edited Dec 30 '18 at 20:35









Peter Mortensen

1,93611323




1,93611323










asked Dec 30 '18 at 13:12









MonkymanMonkyman

242




242








  • 3




    $begingroup$
    Duplicate You do not need a screen to see a real image.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:05














  • 3




    $begingroup$
    Duplicate You do not need a screen to see a real image.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:05








3




3




$begingroup$
Duplicate You do not need a screen to see a real image.
$endgroup$
– Farcher
Dec 30 '18 at 14:05




$begingroup$
Duplicate You do not need a screen to see a real image.
$endgroup$
– Farcher
Dec 30 '18 at 14:05










3 Answers
3






active

oldest

votes


















5












$begingroup$

You can see real images without a screen. Just look through a converging lens. If what you see is upside-down, then you are seeing a real image.



You are only able to use a screen to show where a real image is because light rays physically converge to a point in space.



When you use a screen, the screen "sees" the real image just as if your eye was where the screen was$^*$. Then we see what is reflected from the screen.



For the plane mirror you are just seeing a reflection, just as if the "mirror image" of your world was placed behind where the mirror if located without the mirror actually being there. Seeing things in a mirror is essentially just like seeing things normally.





$^*$ This is neglecting the fact that your eye is also a lens, so in reality you don't want your eye to be exactly at the image.






share|cite|improve this answer











$endgroup$













  • $begingroup$
    I had practical class in which I could not see the real image until I put a screen there
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:18






  • 2




    $begingroup$
    @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:20












  • $begingroup$
    but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:22










  • $begingroup$
    @Monkyman I have added more about the plane mirror
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:25






  • 1




    $begingroup$
    @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:14



















0












$begingroup$

The mirror directs the reflected rays towards you so you see.



If you direct the rays from a lens towards you you will see the image.



So to see the image formed by an optical system the rays need to reach your eyes in some way.






share|cite|improve this answer









$endgroup$





















    -1












    $begingroup$

    This might help.
    Try focussing the sun with a convex mirror on your hand. You can not merely see it. You can feel it. That is a real image.
    You cannot catch a virtual image on a screen. You can catch a real image on a screen. (Just as you could do it on your hand.) It is a more convenient way to see a real image.
    I my school physics lab, we would use pointed needles to determine the distances. We have to adjust the position of the image pin to avoid parallax. When the room was a bit dusty we could actually see the real inverted image of the object pin from the side.






    share|cite|improve this answer









    $endgroup$









    • 1




      $begingroup$
      Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
      $endgroup$
      – Eric Duminil
      Dec 30 '18 at 19:07










    • $begingroup$
      I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
      $endgroup$
      – Dr S T Lakshmikumar
      Dec 31 '18 at 13:05











    Your Answer





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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    5












    $begingroup$

    You can see real images without a screen. Just look through a converging lens. If what you see is upside-down, then you are seeing a real image.



    You are only able to use a screen to show where a real image is because light rays physically converge to a point in space.



    When you use a screen, the screen "sees" the real image just as if your eye was where the screen was$^*$. Then we see what is reflected from the screen.



    For the plane mirror you are just seeing a reflection, just as if the "mirror image" of your world was placed behind where the mirror if located without the mirror actually being there. Seeing things in a mirror is essentially just like seeing things normally.





    $^*$ This is neglecting the fact that your eye is also a lens, so in reality you don't want your eye to be exactly at the image.






    share|cite|improve this answer











    $endgroup$













    • $begingroup$
      I had practical class in which I could not see the real image until I put a screen there
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:18






    • 2




      $begingroup$
      @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:20












    • $begingroup$
      but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:22










    • $begingroup$
      @Monkyman I have added more about the plane mirror
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:25






    • 1




      $begingroup$
      @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
      $endgroup$
      – Farcher
      Dec 30 '18 at 14:14
















    5












    $begingroup$

    You can see real images without a screen. Just look through a converging lens. If what you see is upside-down, then you are seeing a real image.



    You are only able to use a screen to show where a real image is because light rays physically converge to a point in space.



    When you use a screen, the screen "sees" the real image just as if your eye was where the screen was$^*$. Then we see what is reflected from the screen.



    For the plane mirror you are just seeing a reflection, just as if the "mirror image" of your world was placed behind where the mirror if located without the mirror actually being there. Seeing things in a mirror is essentially just like seeing things normally.





    $^*$ This is neglecting the fact that your eye is also a lens, so in reality you don't want your eye to be exactly at the image.






    share|cite|improve this answer











    $endgroup$













    • $begingroup$
      I had practical class in which I could not see the real image until I put a screen there
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:18






    • 2




      $begingroup$
      @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:20












    • $begingroup$
      but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:22










    • $begingroup$
      @Monkyman I have added more about the plane mirror
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:25






    • 1




      $begingroup$
      @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
      $endgroup$
      – Farcher
      Dec 30 '18 at 14:14














    5












    5








    5





    $begingroup$

    You can see real images without a screen. Just look through a converging lens. If what you see is upside-down, then you are seeing a real image.



    You are only able to use a screen to show where a real image is because light rays physically converge to a point in space.



    When you use a screen, the screen "sees" the real image just as if your eye was where the screen was$^*$. Then we see what is reflected from the screen.



    For the plane mirror you are just seeing a reflection, just as if the "mirror image" of your world was placed behind where the mirror if located without the mirror actually being there. Seeing things in a mirror is essentially just like seeing things normally.





    $^*$ This is neglecting the fact that your eye is also a lens, so in reality you don't want your eye to be exactly at the image.






    share|cite|improve this answer











    $endgroup$



    You can see real images without a screen. Just look through a converging lens. If what you see is upside-down, then you are seeing a real image.



    You are only able to use a screen to show where a real image is because light rays physically converge to a point in space.



    When you use a screen, the screen "sees" the real image just as if your eye was where the screen was$^*$. Then we see what is reflected from the screen.



    For the plane mirror you are just seeing a reflection, just as if the "mirror image" of your world was placed behind where the mirror if located without the mirror actually being there. Seeing things in a mirror is essentially just like seeing things normally.





    $^*$ This is neglecting the fact that your eye is also a lens, so in reality you don't want your eye to be exactly at the image.







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited Dec 31 '18 at 14:35

























    answered Dec 30 '18 at 13:16









    Aaron StevensAaron Stevens

    10.2k31741




    10.2k31741












    • $begingroup$
      I had practical class in which I could not see the real image until I put a screen there
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:18






    • 2




      $begingroup$
      @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:20












    • $begingroup$
      but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:22










    • $begingroup$
      @Monkyman I have added more about the plane mirror
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:25






    • 1




      $begingroup$
      @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
      $endgroup$
      – Farcher
      Dec 30 '18 at 14:14


















    • $begingroup$
      I had practical class in which I could not see the real image until I put a screen there
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:18






    • 2




      $begingroup$
      @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:20












    • $begingroup$
      but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
      $endgroup$
      – Monkyman
      Dec 30 '18 at 13:22










    • $begingroup$
      @Monkyman I have added more about the plane mirror
      $endgroup$
      – Aaron Stevens
      Dec 30 '18 at 13:25






    • 1




      $begingroup$
      @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
      $endgroup$
      – Farcher
      Dec 30 '18 at 14:14
















    $begingroup$
    I had practical class in which I could not see the real image until I put a screen there
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:18




    $begingroup$
    I had practical class in which I could not see the real image until I put a screen there
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:18




    2




    2




    $begingroup$
    @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:20






    $begingroup$
    @Monkyman If you had put your eye where the screen was you would have seen the real image. Screens are used to reflect that real image to your eyes.
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:20














    $begingroup$
    but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:22




    $begingroup$
    but then for a virtual image on a plane mirror you need not put your eyes anywhere but you can still comfortably see the image . why is that so ? thanks for helping out
    $endgroup$
    – Monkyman
    Dec 30 '18 at 13:22












    $begingroup$
    @Monkyman I have added more about the plane mirror
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:25




    $begingroup$
    @Monkyman I have added more about the plane mirror
    $endgroup$
    – Aaron Stevens
    Dec 30 '18 at 13:25




    1




    1




    $begingroup$
    @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:14




    $begingroup$
    @AaronStevens With practice or the help of a translucent screen you can see a real image in mid air. The difficulty in seeing the image is that you have to focus on a region without any material reference points. Have a look at the link that I posted in my comment above.
    $endgroup$
    – Farcher
    Dec 30 '18 at 14:14











    0












    $begingroup$

    The mirror directs the reflected rays towards you so you see.



    If you direct the rays from a lens towards you you will see the image.



    So to see the image formed by an optical system the rays need to reach your eyes in some way.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      The mirror directs the reflected rays towards you so you see.



      If you direct the rays from a lens towards you you will see the image.



      So to see the image formed by an optical system the rays need to reach your eyes in some way.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        The mirror directs the reflected rays towards you so you see.



        If you direct the rays from a lens towards you you will see the image.



        So to see the image formed by an optical system the rays need to reach your eyes in some way.






        share|cite|improve this answer









        $endgroup$



        The mirror directs the reflected rays towards you so you see.



        If you direct the rays from a lens towards you you will see the image.



        So to see the image formed by an optical system the rays need to reach your eyes in some way.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 13 at 19:53









        user591849user591849

        313




        313























            -1












            $begingroup$

            This might help.
            Try focussing the sun with a convex mirror on your hand. You can not merely see it. You can feel it. That is a real image.
            You cannot catch a virtual image on a screen. You can catch a real image on a screen. (Just as you could do it on your hand.) It is a more convenient way to see a real image.
            I my school physics lab, we would use pointed needles to determine the distances. We have to adjust the position of the image pin to avoid parallax. When the room was a bit dusty we could actually see the real inverted image of the object pin from the side.






            share|cite|improve this answer









            $endgroup$









            • 1




              $begingroup$
              Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
              $endgroup$
              – Eric Duminil
              Dec 30 '18 at 19:07










            • $begingroup$
              I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
              $endgroup$
              – Dr S T Lakshmikumar
              Dec 31 '18 at 13:05
















            -1












            $begingroup$

            This might help.
            Try focussing the sun with a convex mirror on your hand. You can not merely see it. You can feel it. That is a real image.
            You cannot catch a virtual image on a screen. You can catch a real image on a screen. (Just as you could do it on your hand.) It is a more convenient way to see a real image.
            I my school physics lab, we would use pointed needles to determine the distances. We have to adjust the position of the image pin to avoid parallax. When the room was a bit dusty we could actually see the real inverted image of the object pin from the side.






            share|cite|improve this answer









            $endgroup$









            • 1




              $begingroup$
              Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
              $endgroup$
              – Eric Duminil
              Dec 30 '18 at 19:07










            • $begingroup$
              I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
              $endgroup$
              – Dr S T Lakshmikumar
              Dec 31 '18 at 13:05














            -1












            -1








            -1





            $begingroup$

            This might help.
            Try focussing the sun with a convex mirror on your hand. You can not merely see it. You can feel it. That is a real image.
            You cannot catch a virtual image on a screen. You can catch a real image on a screen. (Just as you could do it on your hand.) It is a more convenient way to see a real image.
            I my school physics lab, we would use pointed needles to determine the distances. We have to adjust the position of the image pin to avoid parallax. When the room was a bit dusty we could actually see the real inverted image of the object pin from the side.






            share|cite|improve this answer









            $endgroup$



            This might help.
            Try focussing the sun with a convex mirror on your hand. You can not merely see it. You can feel it. That is a real image.
            You cannot catch a virtual image on a screen. You can catch a real image on a screen. (Just as you could do it on your hand.) It is a more convenient way to see a real image.
            I my school physics lab, we would use pointed needles to determine the distances. We have to adjust the position of the image pin to avoid parallax. When the room was a bit dusty we could actually see the real inverted image of the object pin from the side.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Dec 30 '18 at 13:39









            Dr S T LakshmikumarDr S T Lakshmikumar

            3084




            3084








            • 1




              $begingroup$
              Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
              $endgroup$
              – Eric Duminil
              Dec 30 '18 at 19:07










            • $begingroup$
              I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
              $endgroup$
              – Dr S T Lakshmikumar
              Dec 31 '18 at 13:05














            • 1




              $begingroup$
              Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
              $endgroup$
              – Eric Duminil
              Dec 30 '18 at 19:07










            • $begingroup$
              I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
              $endgroup$
              – Dr S T Lakshmikumar
              Dec 31 '18 at 13:05








            1




            1




            $begingroup$
            Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
            $endgroup$
            – Eric Duminil
            Dec 30 '18 at 19:07




            $begingroup$
            Your first experience is poorly described and could be dangerous depending on how it is understood. Please clarify, prove that it's safe or remove it.
            $endgroup$
            – Eric Duminil
            Dec 30 '18 at 19:07












            $begingroup$
            I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
            $endgroup$
            – Dr S T Lakshmikumar
            Dec 31 '18 at 13:05




            $begingroup$
            I fail to see what is so dangerous about using a convex lense to focus the sun into the skin. You would feel the heat and move the lense fast enough.
            $endgroup$
            – Dr S T Lakshmikumar
            Dec 31 '18 at 13:05


















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