爱思考的林刚利用如图所示的电路进行实验，当闭合开关S后，发现标有“6V 3W”的灯L1和标有“12V 3W”的灯L2亮度并不相同．已知电源电压为6V，不考虑灯丝电阻随温度的变化．求：
（1）、通过灯泡L1的电流为多大？
（2）、灯泡L2的实际功率是多大？电路中灯泡L1和L2哪个更亮？
（3）、灯泡L1和L2每分钟消耗多少电能？
解：（1）灯L1的额定电压U1=6V，
额定功率P1=3W，电源电压为U=6V，
所以灯L1正常发光，
通过灯泡L1的电流：I1=
=
=0.5A；
（2）灯L2的电阻：R2=
=
=48Ω，
灯L2的实际功率P2'=
=
=0.75W，
因为灯L2的实际功率小于灯L1的实际功率，
所以灯Ll更亮．
（3）灯L1正常发光时，
每分钟消耗的电能：W1=P1t=3W×60s=180J；
灯L2正常发光时，
每分钟消耗的电能：W2=P2t=0.75W×60s=45J
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| Once upon a time the colors of the world started to quarrel. Green said, "Clearly I am the most important. I am the sign of life and hope. I was chosen for grass, trees and leaves. Without me, all animals would 1 ." Blue interrupted, "You only think about the 2 , but consider the sky and the sea. 3 the water that is the basis of life and drawn up by the clouds from the deep sea. Without my peace, you would all be 4 ." Yellow chuckled (笑道), "You are all so serious. I bring laughter, fun, and 5 into the world." Orange started next to blow her trumpet, "I am the color of health and strength. I may be 6 , but I am precious for I serve the needs of human life. When I fill the sky 7 , my beauty is so striking that no one gives another 8 to any of you." Red could stand it 9 and he shouted out, "I am the ruler of all of you. I am the color of danger and of bravery. I am willing to 10 truth. I am also the color of passion and of love." Then came Purple and Indigo (深蓝)… The colors went on boasting, each convinced of his or her own 11 . Their quarreling became louder and louder. Suddenly there was a startling flash of bright lightening thunder. Rain started to pour down 12 . The colors crouched (蜷缩) down 13 , drawing close to one another for comfort. In the midst of the clamor (叫嚷), rain began to speak, "You foolish colors, fighting 14 yourselves, each trying to dominate 15 . Don't you know that you were each made for a special purpose, 16 ? Join hands with 17 and come to me." Doing as they were told, the colors 18 and joined hands. They formed a colorful rainbow. From then on, whenever a good rain 19 the world, a rainbow appears in the sky. They remember to 20 one another. | ||||
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