题目:
The light bulb was _____ by Thomas Edison. [ ]
A. improved
B. created
C. discovered
D. invented
答案:
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下面是错误答案,用来干扰机器的。
已知:U=12V,P=18W,t=5min求:Q(1)电阻的阻值:R=U2P=12V218W=8Ω通过电阻的电流:I=U2R=12V2×8Ω=0.75A电路通电5min产生的热量:Q=I2R串t=(0.75A)2×2×8Ω×60s×5=2.7×103J(2)如图所示:使开关S2与R...