Why is it when the object is placed between focal lenght and 2focal lenght on convex lense the image is virtual and upright while all the other images are real and inverted?
Dear student,
When an object is placed between the focus and centre of curvature of a convex lens then a ray of light AO which is parallel to the principal axis after refraction pass through focus F along the direction OF. While the other ray AC pass through the optical centre C and goes straight without any deviation. These two light rays intersect each other at point A’, beyond the centre of curvature 2F on the other side of the lens. So, in this case the image A’B’ formed is larger then the object, real and inverted.
When an object is placed between the principal focus and optical centre of a convex lens, then a parallel ray of light AO passes through the focus after refraction along the direction OX. while the other ray AC pass through the optical centre and goes straight without any deviation along the direction CY. But, in this case the two refracted light rays i.e. OX and CY are diverging away from one another, so these cannot intersect each other to form a real image on the right side of the convex lens. Thus, the refracted rays OX and CY are extended backward by dotted lines. On extending back, these rays appear to intersect at point A’. Hence, the image A’B’ formed in this case is a virtual image which is formed on the same side of the lens behind the object. Also the image formed is erect and highly enlarged.
So when an object is placed between F and 2 F real and inverted image is formed. In case when the object is between F and Centre of curvature C then the image is virtual and erect
Regards
When an object is placed between the focus and centre of curvature of a convex lens then a ray of light AO which is parallel to the principal axis after refraction pass through focus F along the direction OF. While the other ray AC pass through the optical centre C and goes straight without any deviation. These two light rays intersect each other at point A’, beyond the centre of curvature 2F on the other side of the lens. So, in this case the image A’B’ formed is larger then the object, real and inverted.
When an object is placed between the principal focus and optical centre of a convex lens, then a parallel ray of light AO passes through the focus after refraction along the direction OX. while the other ray AC pass through the optical centre and goes straight without any deviation along the direction CY. But, in this case the two refracted light rays i.e. OX and CY are diverging away from one another, so these cannot intersect each other to form a real image on the right side of the convex lens. Thus, the refracted rays OX and CY are extended backward by dotted lines. On extending back, these rays appear to intersect at point A’. Hence, the image A’B’ formed in this case is a virtual image which is formed on the same side of the lens behind the object. Also the image formed is erect and highly enlarged.
So when an object is placed between F and 2 F real and inverted image is formed. In case when the object is between F and Centre of curvature C then the image is virtual and erect
Regards