Wright, Mark R., 1854- · London : Longmans · leaf 95
Fig. 59. The part of the shadow that receives no light from theluminous body is called the umbra; the part that receives a … Fig. 60. portion of the light from the luminous body is called the pen-umbra. Rectilinear Propagation of Light—Shadows 87 The size of the penumbra depends upon the relative sizesof the luminous and the opaque body. As the size of thesource of hght is reduced, the penumbra is reduced. If theluminous…
Physics
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