涉及电流表和电压表的问题是历年来各地中考中的典型题。其电表的接法经过命题者的精心设计而变化多端,使本来并不复杂的电路结构看上去显得复杂而难以识别。其实,电压表和电流表都是测量仪表,它们的接入并不影响整个电路的结构。电流表内阻很小,可以忽略不计,在电路中可用一段导线取代电流表;电压表内阻很大,可近似认为没有电流通过,在电路中可视为断路点,将电压表连同其接线直接取走 Problems involving ammeters and voltmeters are typical questions that have been examined in various local exams over the years. The connection of the electric meter has undergone meticulous design of the propositioner, which makes the circuit structure, which is not so complicated, seem complicated and difficult to recognize. In fact, voltmeters and ammeters are measurement instruments, and their access does not affect the structure of the entire circuit. The internal resistance of the ammeter is very small and can be neglected. In the circuit, a wire can be used instead of the current meter; the internal resistance of the voltmeter is very large, and it can be considered that no current passes through, and the circuit can be regarded as a disconnection point, and the voltmeter can be directly taken together with its connection. go