Demonstrating the effects of the angle of the sun's rays on the quantity of heat and light received by the earth
Bend a piece of cardboard and make a square tube 4 cm2 in cross section and 32 cm in length. Secure a piece of very stiff cardboard and cut a strip 23 cm long and 2 cm wide. Paste this to single side of the tube with 15 cm extending. Rest the end of the stiff cardboard on the table and incline the tube at an angle of about 25 degrees. Hold a flashlight or lighted candle at the upper end of the tube and mark off the area on the table that is covered by the light by the tube. Repeat the experiment with the tube at an angle of about 15 degrees. Repeat again with the tube vertical. Evaluate the size of the three spots and determine the area of each. Is the quantity of heat and light received from the sun greater when the rays are slanting or direct ?