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电热器的多挡切换问题一直是中考的热点,一方面它考查了学生电学知识的综合应用能力,另一方面也体现了“生活·物理·社会”的新课标理念.笔者就电热器多挡切换的几种情况,结合几组典型例题,作些粗浅探讨,不足之处还望批评指正。一、“加热”、“保温”两挡切换1.串联保温,单独加热即两个电阻串联接在220V家庭电路时保温,单独一个电阻接在同样电路时加热。例题.(09江苏省统考)下表为一台电烤箱的铭牌,其内部简化电路如图1所示,R_1和R_2均为电热丝。
The multi-block switching problem of electric heater has always been a hot spot in the exam, on the one hand it examines the students’ comprehensive application ability of electric knowledge, on the other hand, it embodies the new curriculum standard concept of “life, physics and society” Several multi-block switch case, with several sets of typical examples, for some superficial discussion, shortcomings also hope to criticism and correction. First, the “heating ”, “insulation ” two-block switch 1. Series insulation, heating alone that is connected in series two 220V home circuit insulation, a separate resistor connected to the same circuit heating. (09 Jiangsu Province, the test) The following table is an oven nameplate, the internal circuit is simplified as shown in Figure 1, R_1 and R_2 are heating wire.