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  • 电路线路

     

    Sketch of a battery and light bulb showing a loose wire affecting the circuit.

    Jose made this sketch of a battery and light bulb for science class. If this were a real set up, the light bulb wouldn't work. The problem is the loose wire on the left. It must be connected to the positive terminal of the battery in order for the bulb to light up.
    ::Jose为科学课绘制了电池和灯泡的素描。 如果这是真的装置的话, 灯泡是行不通的。 问题在于左侧的松线。 它必须连接到电池的正端, 以便灯泡亮起来 。

    Q: Why does the light bulb need to be connected to both battery terminals?
    ::问:为什么灯泡需要连接到两个电池终端?

    A: Electric current can flow through a wire only if it forms a closed loop. Charges must have an unbroken path to follow between the positively and negatively charged parts of the voltage source, in this case, the battery.
    ::A:电流只有在形成封闭循环的情况下才能通过电线流动。电荷必须有一个不间断的路径,在电压源正电和负电源部分之间,在这种情况下,在电池之间。

    Electric Circuit Basics
    ::电路基本基本电路

    A closed loop through which current can flow is called an electric circuit . In homes in the U.S., most electric have a voltage of 120 volts. The amount of current (amps) a circuit carries depends on the number and power of electrical devices connected to the circuit. Home circuits generally have a safe upper limit of about 20 or 30 amps.
    ::电流流动的闭路环被称作电路。在美国的住宅中,大多数电能的电压为120伏。电路的电量取决于电路连接的电设备的数量和电源。 电路的安全上限一般为20或30安培。

    Parts of an Electric Circuit
    ::电路部件

    All electric circuits have at least two parts: a voltage source and a conductor. They may have other parts as well, such as light bulbs and switches, as in the simple circuit seen in the Figure . 
    ::所有电路至少有两部分:电压源和导电器,还可能有其他部件,如灯泡和开关,如图3所示的简单电路。

    Parts of an electric circuit: battery, wires, light bulb, and switch.

    • The voltage source of this simple circuit is a battery. In a home circuit, the source of voltage is an electric power plant, which may supply electric current to many homes and businesses in a community or even to many communities.
      ::这种简单电路的电压来源是电池,在家庭电路中,电压来源是电厂,电厂可为社区甚至许多社区的许多家庭和企业提供电流。
    • The conductor in most circuits consists of one or more wires. The conductor must form a closed loop from the source of voltage and back again. In the Figure , the wires are connected to both terminals of the battery, so they form a closed loop.
      ::大多数电路的导体由一个或多个电线组成。导体必须从电压源形成一个闭路循环,然后从电压源和回路形成一个闭路循环。在图中,电线与电池的两个终端连接,因此形成一个闭路循环。
    • Most circuits have devices such as light bulbs that convert electrical energy to other forms of . In the case of a light bulb, electrical energy is converted to light and .
      ::大多数电路都有灯泡等装置,将电能转换成其他形式的电能。对于灯泡而言,电能转换成光和电能。
    • Many circuits have switches to control the flow of current. When the switch is turned on, the circuit is closed and current can flow through it. When the switch is turned off, the circuit is open and current cannot flow through it.
      ::许多电路都有控制电流流动的开关。 当开关打开时, 电路是封闭的, 电路可以流过电路。 当开关关闭时, 电路是开放的, 电路不能流过电路 。

    Circuit Diagrams
    ::电路图图

    When a contractor builds a new home, they use a set of plans called blueprints that show them how to build the house. The blueprints include circuit diagrams. The diagrams show how the wiring and other electrical components are to be installed in order to supply current to appliances, lights, and other electric devices. You can see an example of a very simple circuit in the Figure . Different parts of the circuit are represented by standard circuit symbols. An ammeter measures the flow of current through the circuit, and a voltmeter measures the voltage. A resistor is a passive device that’s primary function converts some of the electrical energy to other forms of energy by limiting the flow of electric current. Remote-controlled cars use resistors in their circuits to control the of the motor. By changing the in the circuit, the car can be made to move faster or slower.
    ::当承包商建造新房子时,他们使用一套称为蓝图的计划,显示他们如何建造房子。蓝图包括电路图。图表显示如何安装电线和其他电气部件,以便向电器、灯和其他电动装置提供电流。图中可以看到一个非常简单的电路的例子。电路的不同部分用标准电路符号代表。一个仪表测量电流通过电路的流量,一个电压计测量电压。一个被动装置,主要功能是限制电流的流动,将一些电能转换为其他形式的能源。遥控汽车在电路中使用阻力器控制电动。通过改变电路路,汽车可以加速或放慢速度。

    A simple circuit diagram showing an ammeter, voltmeter, resistors, and standard circuit symbols.
    The circuit diagram in the middle represents the circuit drawing on the left. On the right are some of the standard symbols used in circuit diagrams.

    Q: Only one of the circuit symbols in the Figure must be included in every circuit. Which symbol is it?
    ::问题:图中的电路符号中只有一个必须包含在每条电路中。哪个符号?

    A: The battery symbol (or a symbol for some other voltage source) must be included in every circuit. Without a source of voltage, there is no electric current.
    ::A:电池符号(或某种其他电压源的符号)必须包含在每个电路中。 没有电压源,就没有电流。

    Watch the video below to learn more about how to draw circuit diagrams:
    ::观察下面的影片, 学习如何绘制电路图:

    Launch the PLIX Interactive below to see how electrons flow through a dry cell battery and the circuit connected to it:
    ::启动下面的PLIX互动, 查看电子如何通过干电池电池和连接它的电路流动:

     

     

    Summary
    ::摘要

    • An electric circuit is a closed loop through which current can flow.
      ::电路是一个闭路环,水流可以畅通无阻。
    • All electric circuits must have a voltage source, such as a battery, and a conductor, which is usually wire. They may have one or more electric devices as well.
      ::所有电路都必须有电压源,如电池和导电器,通常都是电线,还可能有一个或多个电动装置。
    • An electric circuit can be represented by a circuit diagram, which uses standard symbols to represent the parts of the circuit.
      ::电路可以用电路图表示,电路图使用标准符号表示电路的各个部分。

    Review
    ::回顾

    1. What is an electric circuit?
      ::什么是电路?
    2. Which two parts must all electric circuits contain?
      ::所有电路必须包含哪些两部分?
    3. Sketch a simple circuit that includes a battery, switch, and light bulb. Then make a circuit diagram to represent your circuit, using standard circuit symbols.
      ::绘制一个简单的电路, 包括电池、 开关和灯泡。 然后用标准电路符号绘制一个电路图来代表您的电路 。