For a thin convex lens the’focal length for red and blue light is 1.005 m and 0.995 m respectively. What is the dispersive power for that lens medium?

A telescope is such that the power of its two lenses be 0.5D and 20D respectively. What will be the magnifying power of that lens? —

A convex lens of focal lengths 30 cm produces 5 times magnified real image of an object What is the object distance ?

Two convex lenses of focal lengths f_1 and f_2 respectively are placed in contact each other. Then what will be power of their equivalent lens?

If in a plano-convex lens, the radius of curvature of the convex surface is 10cm and the focal length of the lens is 30cm, then what is the refractive index of the material of lens ?

Two convex lenses of focal lengths f_(1) and f_(2) respectively are placed in contact with each other. Then what will be power of their equivalent lens?

A point object is placed on the axis of a thin convex lens of focal length 0.05 m at a distance of 0.2 m from the lens and its image is formed on the axis. If the object is now made to oscillate along the axis with a small amplitude of A cm, then what is the amplitude of oscillation of the image ? [you many assume, 1/(1+x) = 1-x , where x lt lt 1 ]

If the refractive index of convex lens and surrounding medium be mu_1 and mu_2 respectively then for convex lens to act as concave lens when