Nystrom, John W. (John William), 1824-1885 · Philadelphia, J.B. Lippincott · leaf 327
315 Given the direction of the emergent rays a a\ angles e and r to find the angles u and a;,—or the direction of the rays b V. COS. Z = COS. 6 /toa \ , cos. u=mcos.[ 180—z—r). x = 180 —(e+r+u). When e = u, the angle x is smallest.An eye in V will see the candle in the direc-tion b1 b b. 296 Optic?. … 316 Double Convex Lens. f= + ^r . the principal (m-l)(J?+r)* focal distance. o *= optical centre of the lens.
Mechanical engineering · Engineering
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