1.10电流
章节大纲
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Lesson Objectives
::经验教训目标- Define electric current.
::定义电流。
- Relate electric current to materials (Insulators and Conductors).
::电流与材料(导电器和导电器)相对应。
Lesson Vocabulary
::词汇表课程- electric conductor
::电导电导器
- electric current
::电电电流
- electric insulator
::电解器
- resistance
::抗药性
- voltage
::电压电压
Introduction
::导言Have you ever felt a shock? Maybe you had just walked across the carpet and touched something metal? How is this similar to lightning? Believe it or not, they are very similar. They are both discharges of static electricity. Lightning is static electricity on a grand scale. Lightning discharges a lot of electric charge. It happens all at once. Unfortunately, this large discharge is not useful. It is so large and so fast, it cannot be controlled. You can’t plug a toaster into a lightning bolt!
::你是否曾感到震撼?也许你刚刚走过地毯,碰过金属的东西?这和闪电有什么相似之处?信不信由你,它们非常相似。它们都是静电输出。电闪电是大尺度的静电。电闪电是静电。电闪电释放了大量电荷。它同时发生。不幸的是,这种大卸电没有用处。它如此大和如此快,无法控制它。你不能将烤面包机插在闪电线上!For most devices, a much smaller amount of electric charge is needed. It must also be steady. It can't come all in one big jolt. That's why we can't run our homes off of lightning. Our homes need to have a steady and continuous supply of electric current.
::对于大多数装置来说,需要的电费要少得多。 电费也必须稳定。 电费不能完全一振即逝。 这就是为什么我们无法用闪电来管理我们的家。 我们的家需要稳定和持续的电流供应。Introduction to Electric Current
::电流介绍Surely, you have noticed the tall poles along the roadside. Do you know what is on top of those poles? That's right, wires that carry electric current. These wires carry electric current to your home. But what is electric current?
::你确已注意到了路边的高杆,你知道那些杆上面有什么东西吗?是的,电线带电流。电线带电流到你家。但电流是什么?Electric current is actually the flow of electrons. You may recall, an electron is the outer-most particle in an atom. They have a negative charge. Electricity is the continuous flow of these particles. Electrons are able to move through wires. Their speed can even be measured. The SI unit for electric current (or speed) is the ampere (A). Ampere is often shortened to amp. Electric current may flow in just one direction, or it may keep reversing direction.
::电流实际上是电子的流。 您可能记得, 电子是原子中最外缘的粒子。 它们有一个负电荷。 电是这些粒子的连续流。 电是这些粒子的连续流。 电可以通过电线移动。 甚至可以测量电流的速度。 电流( 或速度) 的 SI 单位是 ampere (A) 。 电流通常被缩短为 ampere 。 电流可能只流向一个方向, 或者它可能不断向相反的方向流 。- Direct current (DC) flows in only one direction. Direct current is what is used in devices like flashlights.
::直接电流( DC) 流向只有一个方向。 直接电流是手电筒等装置中使用的电流 。
- Alternating current (AC) flows in two directions. This is the type of current that flows into your home through wires. When you plug something into a wall socket, it is most likely alternating current.
::将当前流向两个方向互换。 这是通过电线流入你家的流流类型。 当您将某东西插入墙套时, 它很可能是交替流 。
Electric Current and Materials (Conductors and Insulators)
::电流和材料(电流和电解器)Electric current cannot go through empty space. Electricity needs something to flow through. Electricity cannot flow through all materials. Some materials resist the flow of electricity. Some materials let electricity pass through easily. Scientists classify these into two groups. These groups are called conductors and insulators.
::电流不能穿过空地。 电力需要通过一些东西流经。 电力不能通过所有材料流经。 有些材料阻拦了电力流。 有些材料让电流很容易通过。 科学家将电流分为两组。 这些组被称为导电器和绝缘器。- Materials that allow electrons to flow freely are called electric conductors . Electricity is able to race through these materials. Copper, aluminum, and steel are good conductors.
::允许电子自由流通的材料被称为电导器。 电力可以通过这些材料进行竞赛。 铜、铝和钢是良好的导电器。
- Materials that resist the flow of electricity are called electric insulators . Instead of racing, the current may travel in slow motion, if at all. Wood, rubber, and plastic are examples of electric insulators.
::阻力电流的材料被称为电绝缘器。 电流不叫电绝缘器,电流可能会缓慢移动,如果有的话。 木、橡胶和塑料是电绝缘器的例子。
You probably know that electric wires are made of metal. They typically have a rubber or plastic coating. Do you know why? Metals are good electric conductors. They offer little resistance to electricity. Most of the current can pass through the wire. Rubber and plastic are good insulators. They offer a lot of resistance. They do not allow much current to pass through. Electricity always seeks the path of least resistance. That is why all the current passes only through a metal wire. It does not pass through the rubber or plastic coating. The plastic coating on the wire is there for your safety.
::你可能知道电线是由金属制成的,它们通常有橡胶或塑料涂层。你知道为什么吗?金属是好的电导器,对电力没有多大的阻力。大部分电流可以穿透电线。橡胶和塑料是很好的绝缘器。它们不允许太多的电流穿透。电力总是在寻找阻力最小的路径。这就是为什么所有电流都通过金属涂层。它不会通过橡胶或塑料涂层。电线上的塑料涂层是为了保证你的安全。These electric cables are made of copper wires surrounded by a rubber coating. Lesson Summary
::经验教训摘要- Electric current is a continuous flow of electric charge. It is measured in amperes (A).
::电流是电荷的连续流动,用安培(A)测量。
- Direct current (DC) flows in just one direction. Alternating current (AC) keeps reversing direction.
::直接流(DC)流只流向一个方向。 交替流(AC)不断逆转方向。
- Electric current needs a material through which to travel. Materials differ in how much they resist electric current.
::电流需要一种可以穿梭的材料。 材料在它们抵抗电流的程度上有所不同。
- Some materials are good conductors of electricity. Electric conductors allow electrons to flow freely.
::有些材料是良好的电力导电器,电导器允许电子自由流通。
- Some materials resist the flow of current. Electric insulators resist the flow of electrons.
::电解器阻抗电子流。
Lesson Review Questions
::经验回顾问题Recall
::回顾- What is electric current?
::什么是电流?
- Describe the difference between conductors and insulators.
::描述导演和绝缘器之间的区别。
- Compare and contrast electric conductors and electric insulators. Give an example of each.
::比较和对比电导器和电解器。请举例说明其中的每个例子。
Points to Consider
::需要考虑的要点In this lesson, you learned about electric current. The next lesson, "Electric Circuits," focuses on the path that electric current travels. Think about a ceiling light with a wall switch. You probably have several in your home.
::在这一课中,你学到了电流。下一个课,“电流电路 ” , 重点是电流的行进路径。 想想一个带墙开关的天花板灯。 您家里可能有几个。- What path does current travel to get from the switch on the wall to the light on the ceiling?
::目前从墙上的开关到天花板上的灯光的路径是什么?
- How do you think the switch controls the flow of current to the light?
::你认为开关如何控制电流流向光线?
Some materials may resist the flow of current. - Define electric current.
