Section outline

  • General

    Collapse all Expand all

  • 电导器和电解器

    Close-up of an old house roof featuring lightning rods with connecting wires.

    Do you see the wires and peaks on top of this old house? They are lightning rods, and their purpose is to protect the building in the event of a lightning strike. Each lightning rod is connected to a wire that goes down the side of the house and into the ground. If lightning strikes the building, it will target the rod and be conducted by the rod and wire into the ground. There the electricity can be safely absorbed. Lightning rods may differ in style, but to work they must be good at conducting electricity.
    ::你看这栋老房子的顶部有铁丝网和山峰吗?这些是闪电杆,其目的是在闪电袭击时保护大楼。每根闪电杆都连接到从房屋侧面向地上的铁丝网。如果闪电击中大楼,它就会瞄准棍子,然后用棍子将电线接入地面。电线可以安全地吸收。电线杆在风格上可能不同,但工作时必须善于供电。

    Electric Current and Matter
    ::电电电电和电电电

    Electrical energy is transmitted by moving electrons in an electric current . In order to travel, electric current needs matter. It cannot pass through empty space. However, matter resists the flow of electric current. That’s because flowing electrons in current collide with particles of matter, which absorb their . Some types of matter offer more or less to electric current than others.
    ::电能是通过电流中电子移动传输的。为了旅行,电流需要很重要。电流不能通过空空空间。然而,电流的流能阻断电流的流动。这是因为电流中的电流电子与吸收电流的物质粒子相碰撞。 某些类型的电流比其他类型的电流多或少。

    Electric Conductors
    ::电导器

    Materials that have low resistance to electric current are called electric conductors . Many metals—including copper, aluminum, and steel—are good conductors of electricity. The outer electrons of metal atoms are loosely bound and free to move, allowing electric current to flow. Water that has even a tiny amount of impurities is an electric conductor as well.
    ::对电流有低抗力的材料称为电导器,许多金属——包括铜、铝和钢——是良好的电导器,金属原子的外部电子松散而自由移动,允许电流流动,甚至少量杂质的水也是电导器。

    Q: What do you think lightning rods are made of?
    ::问题:你认为闪电棒是用什么做的?

    A: Lightning rods are made of metal, usually copper or aluminum, both of which are excellent conductors of electricity.
    ::A:闪电棒是由金属、通常是铜或铝制成的,这两种金属都是极好的电力导电器。

    Electric Insulators
    ::电解器

    Materials that have high resistance to electric current are called electric insulators . Examples include most nonmetallic solids, such as wood, rubber, and plastic. Their atoms hold onto their electrons tightly, so electric current cannot flow freely through them. Dry air is also an electric insulator . 
    ::对电流具有高度抗药性的材料被称为电解器,包括大多数非金属固体,如木材、橡胶和塑料,它们的原子紧紧握在电子上,因此电流不能自由通过电流。 干燥空气也是电解器。

    Q: You may have heard that rubber-soled shoes will protect you if you are struck by lightning. Do you think this is true? Why or why not?
    ::问:你可能听说了,如果被闪电击中,橡皮鞋会保护你。你以为这是真的吗?为什么或为什么不是呢?

    A: It isn’t true. Rubber is an electric insulator, but a half-inch layer on the bottom of a pair of shoes is insignificant when it comes to lightning. The average lightning bolt has 100 million volts and can burn through any insulator, even the insulators on high- voltage power lines.
    ::甲:这不是真的。 橡胶是一种电绝缘器,但一双鞋底部的半英寸层在闪电方面是微不足道的。 平均闪电有1亿伏特,可以在任何绝缘器中燃烧,即使是高压电线上的绝缘器。

    The Path of Least Resistance
    ::最不发达抵抗运动之路

    Look at the electric wires in the Figure . They are made of copper and coated with plastic. Copper is very good conductor, and plastic is a very good insulator. When more than one material is available for electric current to flow through, the current always travels through the material with the least resistance. That’s why all the current passes through the copper wire and none flows through its plastic coating.
    ::看看图中的电线。这些电线是由铜制成的,并涂有塑料。铜是非常好的导电器,塑料是非常好的绝缘器。 当有不止一种材料可供电流流动时,电流总是以最小的阻力穿透材料。 这就是为什么所有电流都通过铜导电线,没有通过塑料涂层。

    Close-up of copper wires coated in plastic, demonstrating conductors and insulators.

    Watch the video below to learn more about conductors and insulators:
    ::更多了解导演和绝缘器:

    Summary
    ::摘要

    • Electricity must travel through matter. All matter offers some resistance to the flow of electrons in an electric current. Some materials resist current more or less than others.
      ::电流必须经过电流。 所有物质都对电流中的电子流动具有一定的阻力。 有些材料的阻力比其他材料的阻力多或少。
    • Materials that have low resistance to electric current are called electric conductors. Many metals are good electric conductors.
      ::对电流抗力低的材料称为电导器,许多金属是好的电导器。
    • Materials that have high resistance to electric current are called electric insulators. Wood, rubber, and plastic are good electric insulators.
      ::对电流具有高度抗药性的材料称为电绝缘器,木材、橡胶和塑料是良好的电绝缘器。
    • When more than one material is available for electric current to flow through, the current always travels through the material with the least resistance. 
      ::当有多种材料供电流通过时,电流总是通过材料,阻力最小。

    Review
    ::回顾

    1. What is an electric conductor? Give examples of good electric conductors.
      ::电动导电器是什么?
    2. Explain why electric current doesn’t flow through rubber.
      ::解释为什么电流不通过橡胶流动。
    3. Jon can see the conductor of the power cord for an electric lamp. Should he use the lamp? Why or why not?
      ::Jon能看到电灯电线的导线,他应该用灯吗?