Questions in Ray Optics and Optical Instruments

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	The magnifying power of a telescope can be increased by
	A simple telescope, consisting of an objective of focal length $60 cm$ and a single eye lens of focal length $5 cm$ is focussed on a distant object is such a way that parallel rays comes out from the eye lens. If the object subtends an angle $2^o$ at the objective, the angular width of the image
	The diameter of the objective of the telescope is 0.1 metre and wavelength of light is 6000 Å. Its resolving power would be approximately
	A photograph of the moon was taken with telescope. Later on, it was found that a housefly was sitting on the objective lens of the telescope. In photograph
	For a telescope to have large resolving power the
	An observer looks at a tree of height 15 m with a telescope of magnifying power 10. To him, the tree appears
	The focal length of objective and eye lens of a astronomical telescope are respectively 2 m and 5 cm. Final image is formed at (i) least distance of distinct vision (ii) infinity. The magnifying power in both cases will be
	For observing a cricket match, a binocular is preferred to a terrestrial telescope because
	To increase the magnifying power of telescope ($f_o$ = focal length of the objective and $f_e$ = focal length of the eye lens)
	Relative difference of focal lengths of objective and eye lens in the microscope and telescope is given as