Phillips, Percy · London : T. C. & E. C. Jack ; New York : Dodge Pub. Co. · leaf 51
have the three screensabout a foot apart. The waves of light emerging from P fall on the secondscreen, and two small fractions of them emerge throughA and B and act like the two sources Sx and S2, in Fig. 28,producing interference bands at the screen Z or theeye-piece E. The bright and dark bands… … Fig. 29.clearer and more numerous when a source of light isused which only gives out waves of a certain definitewave-length. Such sources are produced when certainmetallic salts are placed in the colourless bunsen flame,the most convenient salts for general use being the saltsof sodium such as…
Light
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