判断电路中电表 (电压表、电流表 )读数的变化 ,是综合考查同学们对串联、并联电路特点和欧姆定律掌握程度及其应用这些知识来解决实际问题能力的一种有效办法 ,也是近几年中考常考的内容之一。对于初中生来说 ,在电路中 ,引起电表读数变化的根源是电路中变阻器滑片的滑动 ,或 Judging the changes in the readings of the meter (voltmeter, ammeter) in the circuit is an effective way to comprehensively examine the characteristics of the series and parallel circuits and Ohm’s law and their ability to apply these knowledge to solve practical problems. One of the contents of the entrance exam. For junior high school students, in the circuit, the cause of changes in the reading of the meter is the sliding of the varistor slide in the circuit, or