Questions in Ray Optics and Optical Instruments

Select	Question
	Two thin lenses of focal lengths $f_1$ and $f_2$ are in contact. The focal length of this combination is
	A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
	An equiconvex lens is cut into two halves along (i) $XOX'$ and (ii) $YOY'$ as shown in the figure. Let $f, f', f''$ be the focal lengths of the complete lens, of each half in case (i), and of each half in case (ii), respectively Choose the correct statement from the following
	The sun makes $0.5^o$ angle on earth surface. Its image is made by convex lens of 50 cm focal length. The diameter of the image will be
	The chromatic Aberration in lenses becomes due to
	If aperture of lens is halved then image will be
	When the convergent nature of a convex lens will be less as compared with air
	An achromatic combination of lenses produces
	In a parallel beam of white light is incident on a converging lens, the colour which is brought to focus nearest to the lens is
	A magnifying glass is to be used at the fixed object distance of 1 inch. If it is to produce an erect image magnified 5 times its focal length should be