📚 IGCSE CCEA Physics: Mastering Circuit Analysis | 电路分析考点精讲
Circuit analysis is a cornerstone of the CCEA IGCSE Physics syllabus. This guide systematically covers current, voltage, resistance, power, and the behaviour of components in series and parallel. By mastering these key principles, you will be fully equipped to tackle both theoretical and practical questions in the examination.
电路分析是 CCEA IGCSE 物理教学大纲的基石。本指南系统讲解电流、电压、电阻、功率以及元器件在串联和并联中的行为。掌握这些关键原理，你将能够从容应对考试中的理论和实践问题。
1. Current, Charge and Potential Difference | 电流、电荷与电势差
Electric current is the rate of flow of electric charge. It is given by the equation I = Q / t, where I is current in amperes (A), Q is charge in coulombs (C), and t is time in seconds (s).
电流是电荷流动的速率，公式为 I = Q / t，其中 I 为电流（安培，A），Q 为电荷（库仑，C），t 为时间（秒，s）。
Potential difference (voltage) between two points is the work done per unit charge. The relationship is V = W / Q, where V is voltage in volts (V) and W is work or energy in joules (J).
两点之间的电势差（电压）是单位电荷所做的功。关系式为 V = W / Q，其中 V 为电压（伏特，V），W 为功或能量（焦耳，J）。
An ammeter must be connected in series to measure current, whereas a voltmeter is connected in parallel across the component to measure potential difference.
测量电流时安培表必须串联在电路中，而测量某元器件的电势差时伏特表应并联在该元器件两端。
2. Ohm’s Law and Resistance | 欧姆定律与电阻
Resistance is a measure of the opposition to current flow. It is defined as R = V / I and measured in ohms (Ω).
电阻是衡量对电流阻碍作用的物理量，定义为 R = V / I，单位是欧姆（Ω）。
Ohm’s Law states that the current through a conductor is directly proportional to the potential difference across it, provided temperature remains constant. This linear relationship is represented by the equation V = I × R.
欧姆定律指出，在温度保持不变的条件下，通过导体的电流与导体两端的电压成正比。这一线性关系可用方程 V = I × R 表示。
Not all components obey Ohm’s Law. For example, a filament lamp’s resistance increases as it gets hotter, and a diode only allows current to flow in one direction.
并非所有元器件都遵循欧姆定律。例如，灯丝灯泡的电阻会随着温度升高而增大，而二极管只允许电流单向流动。
3. Factors Affecting Resistance | 影响电阻的因素
The resistance of a wire depends on its length (L), cross-sectional area (A), and the material’s resistivity (ρ). The relationship is R = ρL / A. Longer wires have greater resistance, while thicker wires have lower resistance.
导线的电阻取决于其长度（L）、横截面积（A）以及材料的电阻率（ρ）。关系式为 R = ρL / A。导线越长电阻越大，而导线越粗电阻越小。
Temperature also affects resistance. In metallic conductors, resistance increases with temperature because the ions vibrate more, impeding electron flow. However, in thermistors (NTC), resistance decreases as temperature rises. Light-dependent resistors (LDRs) show a decrease in resistance with increasing light intensity.
温度也会影响电阻。在金属导体中，电阻随温度升高而增大，因为离子振动加剧阻碍电子流动。然而，在负温度系数热敏电阻（NTC）中，电阻随温度升高而减小。光敏电阻（LDR）的电阻随光照增强而降低。
4. Series Circuits | 串联电路
In a series circuit, the current is the same at all points. The total resistance is the sum of individual resistances: Rtotal = R₁ + R₂ + …. The supply voltage equals the sum of the potential differences across each component: Vtotal = V₁ + V₂ + …
在串联电路中，各点的电流相同。总电阻等于各个电阻之和：R总 = R₁ + R₂ + … 。电源电压等于各个元器件两端电势差的总和：V总 = V₁ + V₂ + … 。
Potential difference is divided across resistors in proportion to their resistances: V₁ / V₂ = R₁ / R₂. This principle is used in potential dividers.
电压按电阻的比例分配：V₁ / V₂ = R₁ / R₂。这一原理应用于分压器中。
5. Parallel
Published by TutorHao | IGCSE Physics Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导