中考物理基础知识（十）:第十六章 电压电阻

Basic Physics Knowledge for Senior High School Entrance Exam (10): Chapter 16 Voltage And Resistance

李宏 湖北省十堰市郧阳中学

Li Hong Yunyang High School, Shiyan City, Hubei Province

第十六章 电压电阻-[中考物理基础知识]

Chapter 16 Voltage and Resistance - [Basic Knowledge of Physics for High School Entrance Examination]

97．常见的电压值：家庭照明电路电压220V； 一节干电池1.5V；

Common voltage values: Voltage of household lighting circuit is 220 V; Voltage of a dry cell is 1.5 V;

对人体安全的电压不高于36V； 手机电池电压约3.7V。

The safe voltage for the human body is no higher than 36 V; Voltage of a mobile phone battery is approximately 3.7 V.

98．电压用符号“U”表示，电压的单位是伏特，符号V，还有KV和mV。

Voltage is denoted by the symbol "U". The unit of voltage is the volt, denoted by V, with other units being kV (kilovolt) and mV (millivolt).

99．电压表的使用：

Usage of a voltmeter:

（1）电压表必须与被测用电器并联；

A voltmeter must be connected in parallel with the measured electrical appliance;

（2）电压表的“+”接线柱连接靠近电源正极的一端，“－”接线柱连接靠近电源负极的一端；

The positive (+) terminal of the voltmeter is connected to the end close to the positive pole of the power supply, and the negative (–) terminal is connected to the end close to the negative pole of the power supply;

（3）选择合适的量程（0～3V; 0～15V）。

Select an appropriate measuring range (0～3 V; 0～15 V).

100．串、并联电路电压的规律：

Voltage rules for series and parallel circuits:

（1）串联电路两端的总电压等于各部分电路两端的电压之和；（即U串=U1+U2）

The total voltage across a series circuit is equal to the sum of the voltages across each part of the circuit; (i.e., Useries=U1+U2)

（2）并联电路各支路两端的电压相等，都等于电源电压。（即U并=U1=U2）

The voltages across all branch circuits in a parallel circuit are equal, and all are equal to the voltage of the power supply. (i.e., Uparallel=U1=U2)

101．电阻用“R”表示，单位是欧姆，符号Ω。导体的电阻与导体的材料、长度、横截面积及温度有关。与导体两端的电压和通过的电流无关。

Resistance is denoted by "R". The unit of resistance is the ohm, denoted by Ω. The resistance of a conductor is related to its material, length, cross-sectional area and temperature. It has no relation to the voltage across the conductor or the current passing through it.

102．滑动变阻器：

Sliding rheostat:

（1）原理：通过改变接入电路的电阻线的长度来改变电阻的大小。

Principle: Change the resistance by altering the length of the resistance wire connected to the circuit.

（2）接法：必须“一上一下”

Connection method: Connect to one terminal on the top and one on the bottom of the rheostat.

（3）作用：①保护电路；②改变电路中电流的大小。

Functions: Protect the circuit; Change the magnitude of the current in the circuit.

Explorer of Innovative Thinking

Author: Li Hong

Yunyang High School, Shiyan City, Hubei Province

February 9, 2026