Calendar: 1866-1867 Page 475

APPLIED SCIENCES 477 How many images are there when the luminous point is equally distant from both mirrors number of circular laminae of different radii are placed in order on common axis They are at finite distances from one another such that each subtends greater angle than the one before it at luminous point in front of the least lamina Shew that if any of the laminae except the greatest be removed the total illumination remains the same Define the refractive index of medium candle is placed at given distance in front of thick plane mirror and person looking obliquely into the mirror sees several images of the candle Explain the reason of this and find the When ray of light passes out of one medium into another show that the deviation increases as the angle of incidence in- creases Hence show that when ray of light passes through prism the deviation is in all cases away from the edge of the prism Explain what is meant by the critical angle bright point is placed below the surface of water whose re- fractive index is Pind the aberration of any ray which falls obliquely on and is refracted at the surface Draw figure showing approximately the form of the caustic and describe the appearance of the horizontal base of the reservoir to person looking into it Divergent rays are incident on spherical refracting sur- face Find the geometrical focus and hence find the geo- metrical focus for thin lens with spherical surfaces If tbe focal length of lens is positive show that it is thinnest at the axis bright point is placed at distance from the centre of convex lens upon the axis Show that if plane mirror can be placed behind the lens so as to make the rays incident upon it converge to the bright point after reflection must be between and 1f being the focal length of the lens positions of the several images