List of top Physics Questions on Optical Instruments asked in KEAM

Two convex lenses of different focal lengths are in contact with each other. If the focal length of each lens is doubled, the focal power of the combination

The magnifying power of a telescope of length $76$ cm in the normal adjustment is $75$. Then the focal lengths of the objective and eyepiece lenses are, respectively,

The magnifying power of a simple microscope can be increased by using

Consider a convex lens made of material of refractive index \( n = \frac{3}{2} \) and radius of curvature \( R \). What is the relation between focal length and radius?

Two lenses, one of focal length 20 cm and another of power 4D are placed together, what is the effective power of the combination?

The simple microscope having a lens of focal length 5 cm gives the magnification of (least distance of distinct vision \(= 25\) cm)

When an object is viewed with a light of wavelength \( 6000 \,\text{\AA} \) under a microscope its resolving power is \( 10^4 \). The resolving power of the microscope when the same object is viewed with a light of wavelength \( 4000 \,\text{\AA} \) is

The optical fibres have an inner core of refractive index $ {{n}_{1}} $ and a cladding of refractive index $ {{n}_{2}}, $ such that