Section outline

  • Warning sign indicating the presence of radiation, commonly found in medical environments.

    You may have seen this sign before—maybe in a hospital. The sign means there is danger of radiation in the area. Radiation consists of particles and that are given off by radioactive isotopes, which have unstable nuclei . But you don’t have to go to a hospital to be exposed to radiation. There is radiation in the world all around you.
    ::你也许以前见过这个迹象,也许在医院里。这个迹象意味着该地区存在辐射的危险。 辐射是由粒子和放射性同位素造成的,这些粒子是不稳定的核。 但是,你不必去医院接受辐射照射。 在你周围的世界里都有辐射。

    Radiation in the Environment
    ::辐射在环境中的辐射

    A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive such as uranium. Another source is cosmic rays. These are charged particles that arrive on Earth from outer space. Background radiation is generally considered to be safe for living things. 
    ::低辐射水平自然在环境中发生,称为背景辐射,背景辐射来源之一是岩石,其中可能含有铀等少量放射性物质,另一个来源是宇宙射线,这些是来自外层空间的带电颗粒,一般认为背景辐射对生物安全。

    Dangers of Radiation
    ::辐射危险

    Long-term or high-dose exposure to radiation can harm both living and nonliving things. Radiation knocks electrons out of atoms and changes them to . It also breaks bonds in DNA and other compounds in living things. One source of radiation that is especially dangerous to people is radon. Radon is a radioactive that forms in rocks underground. It can seep into basements and get trapped inside buildings. Then it may build up and become harmful to people who breathe it. Long-term exposure to radon can cause lung cancer.
    ::长期或高剂量辐照会危害生物和非生物物质; 辐射将电子从原子中敲出,将其改变为. 辐射还打破了DNA和生物物质中其他化合物的链条; 对人特别危险的辐射源之一是; 辐射是形成于地下岩石中的放射性; 辐射可以渗入地下室,并被困在建筑物中; 然后,辐射可能会累积起来,对呼吸者有害。 长期接触会导致肺癌。

    Exposure to higher levels of radiation can be very dangerous, even if the exposure is short-term. A single large dose of radiation can burn the skin and cause radiation sickness. Symptoms of this illness include extreme fatigue, destruction of blood cells, and loss of hair.
    ::高辐射水平的照射可能非常危险,即使照射是短期的。 一次大剂量的辐射可能烧伤皮肤并导致辐射疾病。 这种疾病的症状包括极端疲劳、血细胞破坏和头发丧失。

    Nonliving things can also be damaged by radiation. For example, high levels of radiation can weaken by removing electrons. This is a problem in nuclear power plants and space vehicles because they are exposed to very high levels of radiation.
    ::非生物物质也可能受到辐射的损害,例如,高水平的辐射可以通过除去电子而削弱,这是核电厂和空间飞行器的一个问题,因为它们暴露在非常高的辐射水平之下。

    Q: Can you tell when you are being exposed to radiation? For example, can you sense radon in the air?
    ::问题:你能分辨出你何时会受到辐射吗?例如,你能感知到空气中的吗?

    A: Radiation can’t be detected with the senses. This adds to its danger. However, there are other ways to detect it.
    ::A:辐射无法用感官探测到,这增加了辐射的危险。 然而,还有其他方法可以探测到辐射。

    Detecting Radiation
    ::探测辐射

    You generally can’t see, smell, taste, hear, or feel radiation. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one pictured in the Figure , contains atoms of a gas that is ionized if it encounters radiation. When this happens, the gas atoms change to ions that can carry an electric current . The current causes the Geiger counter to click. The faster the clicks occur, the higher the level of radiation. 
    ::通常你看不到、嗅觉、品味、听觉或感知辐射。 幸运的是,盖格计数器等装置可以探测辐射。 盖格计数器像图中所描绘的一样包含气体原子,如果遇到辐射,就会电离化。 发生这种情况时,气体原子会变换成能携带电流的离子。 当前的电流导致盖格计数器点击。 点击速度越快,辐射水平越高。

    A Geiger counter used for detecting radiation levels with a connected probe.

    Using Radiation
    ::使用辐射

    Despite its dangers, has several uses. For example, it can be used to determine the ages of ancient rocks and fossils. It can also be used as a source of power to generate electricity. Radioactivity can even be used to diagnose and treat diseases, including cancer. Cancer cells grow rapidly and take up a lot of glucose for energy. Glucose containing radioactive elements can be given to patients. Cancer cells take up more of the glucose than normal cells do and give off radiation. The radiation can be detected with special machines like the one in the Figure . The radiation may also kill cancer cells. 
    ::放射性甚至可以用来诊断和治疗疾病,包括癌症; 癌症细胞迅速生长并吸收大量葡萄糖来获取能量; 含有放射性元素的甘蔗糖可以提供给病人; 癌症细胞吸收的葡萄糖比正常细胞多,并产生辐射; 辐射可以通过图中的特殊机器探测到。 辐射也可能杀死癌症细胞。

    A PET scanner setup for detecting radiation in medical diagnoses.

    This machine scans a patient’s body and detects radiation.
    ::这台机器扫描病人的身体,探测辐射。

    Summary
    ::摘要

    • A low level of radiation occurs naturally in the environment. This background radiation is generally assumed to be safe for living things.
      ::低辐射水平自然在环境中发生,这种背景辐射一般被认为对生物安全。
    • Long-term or high-dose exposure to radiation can harm living things and damage nonliving materials such as metals.
      ::长期或高剂量辐照可能损害生命,损害金属等非生物物质。
    • One reason radiation is dangerous is that it generally can’t be detected with the senses. It can be detected only with devices such as Geiger counters.
      ::辐射危险的原因之一是一般无法用感官探测到辐射。 只有盖革计数器等装置才能探测到辐射。
    • Radiation has several important uses, including diagnosing and treating cancer.
      ::辐射有若干重要用途,包括诊断和治疗癌症。

    Review
    ::回顾

    1. What are two sources of background radiation?
      ::两种背景辐射来源是什么?
    2. How can radiation harm living things?
      ::辐射如何伤害生命?
    3. What is radon, and why is it harmful to people?
      ::是什么,为什么对人有害?
    4. How does a Geiger counter detect radiation?
      ::盖革计数器如何探测到辐射?
    5. What are some uses of radiation?
      ::辐射有什么用?

    Explore More
    ::探索更多

    Watch the video about uses of radiation, and then answer the questions below. 
    ::观看关于使用辐射的视频, 然后回答下面的问题。

    1. Alpha radiation is used in smoke alarms. Explain how a smoke alarm uses this form of radiation.
      ::烟雾警报器使用阿尔法辐射,解释烟雾警报器如何使用这种辐射形式。
    2. Identify a use of beta radiation, and explain how it works.
      ::识别贝塔辐射的使用, 并解释它是如何运作的 。
    3. List three uses of gamma radiation, and describe one of them in detail.
      ::列出伽马辐射的三种用途,并详细描述其中一种用途。

    Resources
    ::资源