Questions in Ray Optics and Optical Instruments

Select	Question
	The radius of the convex surface of plano-convex lens is 20 cm and the refractive index of the material of the lens is 1.5. The focal length of the lens is
	A combination of two thin convex lenses of focal length 0.3 m and 0.1 m will have minimum spherical and chromatic aberrations if the distance between them is
	A bi-convex lens made of glass (refractive index 1.5) is put in a liquid of refractive index 1.7. Its focal length will
	Spherical aberration in a lens
	The focal lengths of convex lens for red and blue light are 100 cm and 96.8 cm respectively. The dispersive power of material of lens is
	The power of an achromatic convergent lens of two lenses is $+ 2D$. The power of convex lens is $+ 5D$. The ratio of dispersive power of convex and concave lens will be
	The focal lengths for violet, green and red light rays are ${{f}_{V}},{{f}_{G}}$and ${{f}_{R}}$ respectively. Which of the following is the true relationship
	Two lenses of power + 12 and – 2 diopters are placed in contact. The combined focal length of the combination will be
	When light rays from the sun fall on a convex lens along a direction parallel to its axis
	A convex lens is in contact with concave lens. The magnitude of the ratio of their focal length is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths