电压表和电流表的误差及读数,吉林省乾安县第四中学 131400 金迎时 E-mail:jys200512163.com 新人教版 新课标高考地区 会员社区用户名：jys200512163.com,实验室中的电压表和电流表由于自身制造的原因存在较大的误差，根据技术标准为2.5级表，规定每次测量电表自身最大允许误差不超过量程的2.5%。,即:最大误差量程X2.5%,例如：在描绘小灯泡伏安特性曲线实验中，电压表和电流表的示数如实物图所示。电压表的读数为_v，电流表的读数为_A。,0.1V,0.075V,0.05V,1.45V,说明：如果按“1/10估读”，0.01V，与自身最大误差相比，读数就失去意义了。,0.02A,0.015A,0.01A,0.23A,说明：如果按“1/10估读”，0.002A，与自身最大误差相比，读数就失去意义了。,0.1A,0.075A,0.05A,2.35A,说明：如果按“1/10估读”，0.01A，与自身最大误差相比，读数就失去意义了。,0.5V,0.375V,0.25V,9.2V或9.3V,说明：如果按“1/10估读”，0.05V，与自身最大误差相比，读数就失去意义了。,根据上述分析，学生实验用的2.5级电表的读数，根据电表自身误差采取“1/2估读”是合理的。,结论,0.02A,0.015A,0.01A,0.27A,练习,0.57A,0.1A,0.075A,0.05A,1.70A,2.00A,0.1V,0.075V,0.05V,1.41V,2.00V,0.5V,0.375V,0.25V,8. 1V,12.0V,思考：对于较为精密的电表，如图达到0.5级。按照前面讲过的道理，想一想应该怎样读数呢？,学以致用,