Questions in Ray Optics and Optical Instruments

Select	Question
	A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a
	A convex lens is used to form real image of an object on a screen. It is observed that even when the positions of the object and that screen are fixed there are two positions of the lens to form real images. If the heights of the images are 4 cm and 9 cm respectively, the height of the object is
	A convex lens of power + 6D is placed in contact with a concave lens of power – 4D. What is the nature and focal length of the combination
	A double convex lens of glass of $\mu = 1.5$ has radius of curvature of each of its surface is 0.2 m. The power of the lens is
	A lens of focal power 0.5 D is
	A lens which has focal length of 4 cm and refractive index of 1.4 is immersed in a liquid of refractive index 1.6, then the focal length will be
	A convex lens has 9 cm focal length and a concave lens has – 18 cm focal length. The focal length of the combination in contact will be
	A double convex thin lens made of glass of refractive index 1.6 has radii of curvature 15 cm each. The focal length of this lens when immersed in a liquid of refractive index 1.63 is
	A lens of power + 2 diopters is placed in contact with a lens of power – 1 diopoter. The combination will behave like
	Chromatic aberration of lens can be corrected by