题干

三个相同的电阻,分别通过如图甲、乙、丙所示的交变电流,三个图中的I0和周期T相同。下列说法中正确的是(  )

A:在相同时间内三个电阻发热量相等

B:在相同时间内,甲、乙发热量相等,是丙发热量的2倍

C:在相同时间内,甲、丙发热量相等,是乙发热量的1/2

D:在相同时间内,乙发热量最大,甲次之,丙的发热量最小

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答案(点此获取答案解析)

C

同类题2

    I'm Alfred. I was born with a problem in my backbone and mobility(行走能力)was a big challenge, but thanks to my teachers and friends, my school life was excellent.
    My friends and I used to sit together and have lots of fun. Whenever we got a free period, we used to start shouting or play games. I would take part in all competitions, such as poetry writing, story writing and painting and all activities like Teachers' Day or anybody's birthday and had much fun.
    My English teacher was very tall. The moment she would enter the class, we would all sit quiet and open the books. She would encourage me by giving me important assignments and also morning news to read during the assembly. She would come down and hear my English debate(辩论), which made me participate in all debate competitions.
    The same was true of my biology and science teacher. She was very nice and sweet. She would always give me extra information on the biology project. I could not go to the lab for the practicals (lessons or exams in science, cooking etc. in which you have to do or make something yourself rather than write or read about it), so she would bring the lab down and help me with the biology and science practicals and would give me excellent marks.
    My friends made me monitor and the naughty boys listen to me. My friends used to help me with my notes if I was absent. My teachers always gave me important project work and I felt proud when they patted me on the back after I finished it quickly and correctly.
I was never shouted at or made fun of or scolded(批评) by any of my friends and teachers. Today I saw the terrible punishments given to students on television news. I felt very sad.
    I really want to express my love and thanks to all my wonderful teachers and friends, without whom my school life would not have been so excellent and unforgettable. I really pray to God that each child in the world is blessed with caring teachers and wants to attend school every day.