Questions in Ray Optics and Optical Instruments

Select	Question
	The ray diagram could be correct
	A thin convex lens of refractive index 1.5 has a focal length of 15 cm in air. When the lens is placed in liquid of refractive index 4/3 , its focal length will be
	A glass lens is placed in a medium in which it is found to behave like a glass plate. Refractive index of the medium will be
	If ${{I}_{1}}$ and ${{I}_{2}}$ be the size of the images respectively for the two positions of lens in the displacement method, then the size of the object is given by
	A convex lens of crown glass ($ =1.525$) will behave as a divergent lens if immersed in
	A divergent lens will produce
	The minimum distance between an object and its real image formed by a convex lens is
	An object is placed at a distance of 20 cm from a convex lens of focal length 10 cm. The image is formed on the other side of the lens at a distance
	Two thin lenses, one of focal length + 60 cm and the other of focal length – 20 cm are put in contact. The combined focal length is
	A double convex lens of focal length 20 cm is made of glass of refractive index 3 / 2. When placed completely in water ${{(}_{a}}{{\mu }_{w}}=4/3)$, its focal length will be