Gilbert light experiments for boys . Remove the shutter,stand the mirror onthe table in the sun-light, and focus thesunlight on a strip ofpaper inch wide(Fig. 99). Is the pic-ture of the sun roundand very bright? Experiment No. 57. Fig* 97, You see a brilliant focus in dusty airThe focus is very hot. Focus the sunlight on your hand withthe concave mirror (Fig. 100). Is it hot? It is, because all theheat of the sunlight is concentrated at the focus. Experiment No. 58. To light a match with sunlight. Placea match in front of a narrow strip of paper (Fig. 101) and focusthe sunlight on the head. D
Gilbert light experiments for boys . Remove the shutter,stand the mirror onthe table in the sun-light, and focus thesunlight on a strip ofpaper inch wide(Fig. 99). Is the pic-ture of the sun roundand very bright? Experiment No. 57. Fig* 97, You see a brilliant focus in dusty airThe focus is very hot. Focus the sunlight on your hand withthe concave mirror (Fig. 100). Is it hot? It is, because all theheat of the sunlight is concentrated at the focus. Experiment No. 58. To light a match with sunlight. Placea match in front of a narrow strip of paper (Fig. 101) and focusthe sunlight on the head. Does the match light? Experiment No. 59. A magic cannon. Stick a needle intothe under side of a cork and stick a match on the other end of the needle (Fig. 102),with a small piece ofpaper at one side of thehead. Insert the stopperin an empty bottle, focusthe sunlight on thematch head through theglass sides (Fig. 103).Does the match lightand are the cork, nee-dle, and match drivenout with a satisfactory You see the light spread P°P ?. 66 GILBERT BOY ENGINEERING ? The lighted matchheats the air and theexpanding air drivesout the cork. Experiment No. length of con-cave mirror. Focusthe sunlight on a nar-row piece of paperand measure the dis-tance between theback of the mirror and the paper. This is the focal length ofthe mirror. Do you find it to be about two inches ? Experiment No. 61. Focal length of convex mirror. Maketwo pencil dots just 2 inches apart on a piece of cardboard andbetween these punch two holes just 1 inch apart. Hold thecardboard between the convex mirror and the sun and move ituntil the light which passes through the holes 1 inch apart isreflected to the dots 2 inches apart, and measure the distancefrom the back of the mirror to the card. This is the focal Fig. 99. You see a brilliant picture of the sun
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscientificrecreation
