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Two concave lenses L1 and L2 are kept in contact with each other. If the space between the two lenses is filled with a material of smaller refractive index, the magnitude of the focal length of the combination
We know that,
Here, d=0, hence F increases.
Figure (18-Q3) shows three transparent media of refractive indices μ1, μ2 and μ3. A point object O is placed in the medium μ2. If the entire medium on the right of the spherical surface has refractive index μ1, the image forms at O’. If this entire medium has refractive index μ3, the image forms at O’’. In the situation shown,
A point object O is placed on the principal axis of a convex lens of focal length f= 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. An eye is placed 60 cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is