Gilbert light experiments for boys . Fig. 28. The spot is dark by re-fleeted light Fig. 27. The light is one-ninth as strong onB as on A when B is 3 feet from the candle square inches. Place A 1 foot fromthe candle and B 2 feet. Does thelight which passes through 1square inch in A cover 4 squareinches on B? Is it, therefore, onlyone-fourth as intense on B as it ison A? Place B 3 feet from thecandle. Does the light now cover9 square inches? Is it, therefore,only one-ninth as intense? Thisproves that the intensity of lightvaries inversely as the square ofthe distance. Experiment No. 16. A grease
Gilbert light experiments for boys . Fig. 28. The spot is dark by re-fleeted light Fig. 27. The light is one-ninth as strong onB as on A when B is 3 feet from the candle square inches. Place A 1 foot fromthe candle and B 2 feet. Does thelight which passes through 1square inch in A cover 4 squareinches on B? Is it, therefore, onlyone-fourth as intense on B as it ison A? Place B 3 feet from thecandle. Does the light now cover9 square inches? Is it, therefore,only one-ninth as intense? Thisproves that the intensity of lightvaries inversely as the square ofthe distance. Experiment No. 16. A greasedspot. Rub a small piece of butteron the center of a piece of paperand melt it. Look at the spot by reflectedlight (Fig. 28). Is the spot dark?Look at it by transmitted light 22 GILBERT BOY ENGINEERING
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscientificrecreation
