中考物理基础知识（十一）:第十七章 欧姆定律

Basic Physics Knowledge for Senior High School Entrance Exam (11): Chapter 17 Ohm's Law

李宏 湖北省十堰市郧阳中学

Li Hong Yunyang High School, Shiyan City, Hubei Province

第十七章 欧姆定律-[中考物理基础知识]

Chapter 17: Ohm's Law [Basic Knowledge of Physics for the High School Entrance Exam]

103．欧姆定律：导体中的电流跟导体两端的电压成正比，跟导体的电阻成反比。公式：I=U/R

Ohm's Law:The current through a conductor is directly proportional to the voltage across its ends and inversely proportional to its resistance.

104．电阻的串联和并联：

R串=R1+R2 （R串大于R1，R2）

Series and Parallel Resistances: R_series = R₁+ R₂ (R_series is greater than R₁and R₂)

并联电阻：1/R并=1/R1+1/R2(R并小于R1，R2)

Parallel Resistors: 1/R_parallel = 1/R₁+ 1/R₂(R_parallel is less than R₁and R₂)

105．测小灯泡的电阻

Measuring Resistance of a Light Bulb:

（1）原理：欧姆定律

Principle: Ohm's Law

（2）方法：伏安法。

Method: Voltmeter-ammeter method (V-A method)

（3）注意事项：

Precautions:

①连接电路时开关应处于断开状态；

The switch should be open when connecting the circuit.

②闭合电路前滑动变阻器的滑片应调到阻值最大处；

Before closing the circuit, adjust the rheostat slider to its maximum resistance position.

③接通电路后，调节滑动变阻器使小灯泡两端的电压为额定电压，多次测量时从该电压逐次降低。

After powering the circuit, adjust the rheostat to set the bulb's voltage to its rated value. For subsequent measurements, reduce the voltage incrementally.

④应多次测量，最后计算电阻的平均值。

Perform multiple measurements and calculate the average resistance.

Explorer of Innovative Thinking

Author: Li Hong

Yunyang High School, Shiyan City, Hubei Province

February 9, 2026