📚 IB Physics: Current and Circuits Key Points | IB物理：电流与电路考点精讲
Electric current and circuits form a fundamental part of the IB Physics syllabus. This article covers the essential definitions, laws, and problem-solving techniques you need to know. Whether you are preparing for exams or revising the topic, these key points will help you build confidence and avoid common mistakes.
电流与电路是IB物理课程的基础模块。本文将涵盖必备的定义、定律和解题技巧。无论你是在备考还是复习本章节，这些考点都会帮助你建立信心并避免常见错误。
1. Electric Current | 电流
Electric current is the rate of flow of electric charge. In a circuit, charge carriers such as electrons move through a conductor. The SI unit of current is the ampere (A), defined as one coulomb of charge passing a point per second.
电流是电荷流动的速率。在电路中，自由电子等载流子通过导体运动。电流的国际单位是安培（A），定义为每秒通过某一点的电荷量为1库仑。
I = ΔQ / Δt
Conventional current is defined as flowing from the positive terminal to the negative terminal of a battery. However, in a metal wire, electrons actually flow in the opposite direction. Always remember that current is a scalar quantity, even though it has a direction associated with it.
规定电流方向是从电池的正极流向负极。然而在金属导线中，电子实际流向相反方向。请
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