“1”两表有无读数问题电流表和电压表有没有读数关键是看有没有电流流过电表,如若有电流流过电表,则电压表、电流表就有读数,否则没有。例:如图1所示,在匀强磁场中MN和PQ是两条平行金属轨道,而ab和cd为串有电压表和电流表的两根金属棒。当两棒以相同的速度向右运动时,电压表与电流表均没有读数,因为回路没有电流。 “1” Whether or not there are reading problems on the two tables The key to whether the ammeter or voltmeter has a reading or not is to see if there is a current flowing through the meter. If there is a current flowing through the meter, the voltmeter and the ammeter will have a reading, otherwise it will not. Example: As shown in Figure 1, MN and PQ are two parallel metal tracks in a uniform magnetic field, while ab and cd are two metal bars with a voltmeter and an ammeter. When both bars move to the right at the same speed, neither the voltmeter nor the ammeter reads because the loop has no current.