Light visible and invisible : a series of lectures delivered at the Royal Institution of Great Britain, at Christmas, 1896 (1897)
Thompson, Silvanus Phillips, 1851-1916, Royal Institution of Great Britain · New York : Macmillan · leaf 34
theshadows are equallydark, then you knowthat the illuminationof each is equal. Buta better way is toarrange matters thatthe two illuminatedpatches are actuallysuperposed. Here isa very simple andeffective way of doingit. Two pieces ofwhite cardboard, Aand B (Fig. 7), form-ing a V-shape, are… … i8 LIGHT lect. surface of B is seen through the slots in A. If theillumination of A is duller than that of B the slots willseem dark between the brighter bars of the front card;but if the illumination of A is brighter than that of Bthen the slots will seem bright between dull bars.1 Bymoving one of…
Light · X-rays
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