Calendar: 1886-1887 Page 696

698 APPLIED SCIENCES Describe method of comparing the intensities of two sources of light ray of light is incident perpendicularly upon one of the two faces of right-angled isosceles glass prism which bound the right angle Draw picture shewing the sub- sequent path of the ray and give reasons for your construction What is the difference between real and virtual image of an object Explain and illustrate by sketch the formation of one of each kind State generally the effect of lens upon ray of light passing through it Shew how with double-convex lens an image of lighted candle may be seen inverted and mag- nified inverted and diminished erect and magnified Describe the principal parts of spectroscope Explain clearly in what ways the spectroscope has been used to deter- mine the constitution of the Sun and discuss the evidence obtained by its means Shew how the refraction of light by plane surface is accounted for by the wave theory What is the meaning of the refractive index in connection with this theory candle is placed at distance of 15 inches in front of concave mirror whose radius of curvature is 20 inches find the position of the image of the candle and find how far the image will move on pushing the candle inch nearer to the mirror What is meant by Interference of light' An isosceles prism of glass with one angle very nearly equal to two right angles is placed with its two equal faces equidistant from point of light describe and explain the appearance presented on screen at some distance behind the prism 10 Explain in what way beam of ordinary light is changed in passing through crystal of Iceland spar With two NicoPs prisms crossed so as to allow no light to pass describe and account for the change produced on introducing between the prisms plate of glass which is subject to mechanical strain or which has been suddenly cooled