Transformers: Voltage and Turns Ratio | 变压器：电压与匝数比

📚 Transformers: Voltage and Turns Ratio | 变压器：电压与匝数比

Transformers are essential devices in the electrical power grid. They allow high-voltage transmission over long distances and low-voltage use in homes. For Edexcel IGCSE Science, you need to know the structure, the principle of operation, and the key transformer equation.

变压器是电网中至关重要的设备，既能实现高压远程输电，又能把电压降到家庭用电水平。在爱德思 IGCSE 科学课程中，你需要掌握其结构、工作原理以及核心公式。

1. What Is a Transformer? | 什么是变压器？

A transformer is a device that changes the size of an alternating voltage. It has no moving parts and works by electromagnetic induction.

变压器是一种改变交流电压大小的装置。它没有活动部件，依靠电磁感应工作。

• A transformer can increase the voltage.

  变压器可以升高电压。

• A transformer can decrease the voltage.

  变压器也可以降低电压。

• The coil connected to the input is called the primary coil.

  连接输入端、通入交流电的线圈称为初级线圈。

• The coil connected to the output is called the secondary coil.

  连接输出端、产生感应电压的线圈称为次级线圈。

2. Why Transformers Only Work with Alternating Current | 为什么变压器只能使用交流电

A transformer needs a changing magnetic field to induce a voltage in the secondary coil. Alternating current changes direction many times per second, so it creates a continuously changing magnetic field.

变压器需要变化的磁场才能在次级线圈中感应出电压。交流电每秒多次改变方向，因此能产生持续变化的磁场。

Direct current flows in one direction and produces a steady magnetic field. A steady field does not induce a continuous voltage in the secondary coil, so a transformer does not work with d.c.

直流电只沿一个方向流动，产生的是恒定磁场。恒定磁场不能在次级线圈中持续感应出电压，所以变压器不能用直流电工作。

3. Structure of a Transformer | 变压器的结构

A simple transformer consists of a primary coil and a secondary coil wound around a soft iron core.

一个简单的变压器由初级线圈、次级线圈和软铁芯组成。

4. How a Transformer Works |

Published by TutorHao | IGCSE Science Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）