A Convex Lens Is Placed Between An Object And A Screen Which Are A Fixed Distance Apart. For One Position Of The Lens The Magnification Of The Image Obtained On The Screen Is m1. When The Lens Is Moved By A Distance d, The Magnification Of The Image Obtained On The Same Screen Is m2. The Focal Length Of The Lens Is (m1 > m2).      

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A convex lens is placed between an object and a screen which are a fixed distance apart. For one position of the lens the magnification of the image obtained on the screen is m1. When the lens is moved by a distance d, the magnification of the image obtained on the same screen is m2. The focal length of the lens is (m1 > m2).      


Correct option is


For the first position of the lens, m1 = v/u. For the conjugate (second) position, since u and v are interchanged, we have






A thin convergent glass lens (μg = 1.5) has a power of +5.0 D. When this lens is immersed in a liquid of refractive index μl it acts as a divergent lens of focal length 100 cm. The value of  must be   


The distance between an object and a divergent lens is m times the focal length of the lens. The linear magnification produced by the lens will be equal to  


When a telescope is in normal adjustment, the distance of the objective from the eyepiece is found to be 100 cm. If the magnifying power of the telescope, at normal adjustment, is 24, the focal lengths of the lenses are


Monochromatic light is refracted from air into glass of refractive index μ. The ratio of the wavelengths of the incident and refracted waves is


The layered lens shown in fig. is made of two kinds of glass. A point source of light is placed on its principal axis. If reflections from the boundaries between layers are ignored, the lens will form



How much time will light take to transverse a glass slab of thickness 10 cm and refractive index 1.5?


A glass prism ABC of refractive index 1.5 is immersed in water of refractive index 4/3 as shown in fig. A ray of light incident normally on face AB is totally reflected at face AC if  



What is the relation between refractive indices μμ1 and μ2 if the behavior of light rays is as shown in fig.



A lens forms a sharp image on a screen. On inserting a parallel sided glass slab between the lens and the screen, it is found necessary to move the screen a distance d away from the lens is order to focus the image sharply. If the refractive index of glass relative to air is μ, the thickness of the glass slab is given by


A vessel of depth t is half filled with oil of refractive index  and the other half is filled with water of refractive index . The apparent depth of the vessel when viewed from above is