# The circuit rule

## 1. Basic

串联：一条电流不分叉的路径(或直线)上多个元件

并联：两条平行线之间的两条垂线分别有元件

并联，电流相加，电压不变，电阻=$$\frac{(R1 \times R2)}{(R1+R2)}$$

串联，电流不变，电压相加(值从+到-绕闭合线路到0)，电阻=R1+R2

## 2. General Method

电流源模型变电压源模型，并联变串联，$$U=I \times R$$

电阻留着不变

电压源模型变电流源模型，串联变并联，$$I=U \div R$$

变化时电压+方向爲电流箭头方向

## 3. Special Situation

二端元件串联，电流不变 --> 与理想电流源串联，电流不变 --> 并联电路，电压不变 --> 既然在那条线上电压、电流都不变，还要那个电阻有何用？直接删掉。


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://yingshaoxo.gitbook.io/university-notes/electrical-engineering/dc/the-circuit-rule.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.