18.4 波粒理论
章节大纲
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What a beautiful sunset! You probably know that sunlight travels in waves through space from the sun to Earth. But do you know what light really is? Is it just , or is it something else? In this article you’ll find out that light may be more than it seems.
::多么美丽的日落! 你可能知道阳光在从太阳到地球的宇宙中波涛地穿梭。 但你知道什么是光吗?它只是,还是其他东西?在这篇文章中你会发现光可能比表面看起来更亮。The Question
::问 问 问 问 问Electromagnetic radiation , commonly called light, is the transfer of energy by . These waves consist of vibrating electric and magnetic fields. Where does electromagnetic energy come from? It is released when electrons return to lower energy levels in atoms. Electromagnetic radiation behaves like continuous waves of energy most of the time. Sometimes, however, electromagnetic radiation seems to behave like discrete, or separate, particles rather than waves. So does electromagnetic radiation consist of waves or particles?
::电磁辐射,通常称为光,是能量的转移。这些波包括振动电磁场和磁场。电磁能来自何处?当电子恢复到原子中较低的能量水平时,电磁能就会释放出来。电磁辐射行为大部分时间都像连续的能量波。然而,电磁辐射有时似乎表现得像离散或分离的粒子,而不是波。电磁辐射由波或粒子组成吗?The Debate
::辩论 辩论 辩论 辩论This question about the nature of electromagnetic radiation was debated by scientists for more than two centuries, starting in the 1600s. Some scientists argued that electromagnetic radiation consists of particles that shoot around like tiny bullets. Other scientists argued that electromagnetic radiation consists of waves, like or water waves. Until the early 1900s, most scientists thought that electromagnetic radiation is either one or the other and that scientists on the other side of the argument were simply wrong.
::有关电磁辐射性质的问题在科学家们辩论了两个多世纪后,从1600年代开始。一些科学家认为电磁辐射是由粒子组成的,这些粒子像小子弹一样到处发射。其他科学家则认为电磁辐射是由波或水波组成的。 直到1900年代初,大多数科学家认为电磁辐射是其中之一,而科学家们在争论的另一面则是完全错误的。Q: Do you think electromagnetic radiation is a wave or a particle?
::问题:你认为电磁辐射是波还是粒子?A: Here’s a hint: it may not be a question of either-or. Keep reading to learn more.
::答:这里有个提示:也许这不是一个要么要么要么的问题。继续阅读以学习更多。A New Theory
::一个新理论In 1905, the physicist Albert Einstein developed a new theory about electromagnetic radiation. The theory is often called the wave-particle theory . It explains how electromagnetic radiation can behave as both a wave and a particle. Einstein argued that when an returns to a lower and gives off electromagnetic energy, the energy is released as a discrete “packet” of energy. We now call such a packet of energy a photon . According to Einstein, a photon resembles a particle but moves like a wave. You can see this in the Figure . The theory states that waves of photons traveling through space or matter make up electromagnetic radiation.
::1905年,物理学家艾伯特·爱因斯坦开发了电磁辐射的新理论。理论通常被称为波波粒理论。它解释了电磁辐射如何同时作为波和粒子。爱因斯坦认为,当返回低端并释放出电磁能量时,能量会以离散的“组合”能源的形式释放出来。我们现在将这种能量包称为光子。根据爱因斯坦,光子类似于粒子,但移动就像波。在图中可以看到这一点。该理论指出,光子在空间或物质中移动的波构成电磁辐射。Energy of a Photon
::光子的能量A photon isn’t a fixed amount of energy. Instead, the amount of energy in a photon depends on the frequency of the electromagnetic wave. The frequency of a wave is the number of waves that pass a fixed point in a given amount of time, such as the number of waves per second. In waves with higher frequencies, photons have more energy.
::光子不是固定的能量量。 相反,光子中的能量量取决于电磁波的频率。 波的频率是在一定时间内通过固定点的波数,如每秒波数。 在频率较高的波中,光子的能量量更多。Evidence for the Wave-Particle Theory
::波粒理论的证据After Einstein proposed his theory, evidence was discovered to support it. For example, scientists shone laser light through two slits in a barrier made of a material that blocked light. You can see the setup of this type of in the Figure . Using a special camera that was very sensitive to light, they took photos of the light that passed through the slits. The photos revealed tiny pinpoints of light passing through the double slits. This seemed to show that light consists of particles. However, if the camera was exposed to the light for a long time, the pinpoints accumulated in bands that resembled interfering waves. Therefore, the experiment showed that light seems to consist of particles that act like waves.
::爱因斯坦提出他的理论后,发现了支持理论的证据。例如,科学家们在屏障中用屏蔽光材料制成的屏障中用两条斜线照射激光光。你可以在图中看到这种类型的设置。使用对光非常敏感的特别照相机,他们拍摄了穿过光条的灯光照片。照片显示光线通过双条斜线的微小点。这似乎显示光线是由粒子组成的。但是,如果相机长期暴露在光线下,那么在类似干扰波的波段中就会发现。因此,实验表明光线似乎由像波一样的粒子组成。Use the PLIX Interactive below to observe how light particles behave like waves as they diffract through a single slit and create patterns due to their interference:
::使用下面的PLIX互动来观察光粒子如何表现像波浪,Summary
::摘要-
Electromagnetic radiation behaves like waves of energy most of the time, but sometimes it behaves like particles. From the 1600s until the early 1900s, most scientists thought that electromagnetic radiation consists either of particles or of waves but not both.
::大部分时间,电磁辐射行为都像能量波,但有时却像粒子。 从1600年代到1900年代初,大多数科学家认为电磁辐射由粒子或波组成,但并非两者兼有。 -
In 1905, Albert Einstein proposed the wave-particle theory of electromagnetic radiation. This theory states that electromagnetic energy is released in discrete packets of energy—now called photons—that act like waves.
::1905年,艾伯特·爱因斯坦提出了电磁辐射的波粒理论。 该理论指出电磁能量释放在离散的能量包中,即现在称为光子的能量包中,这就像波浪一样。 -
After Einstein presented his theory, scientists found evidence to support it. For example, double-slit experiments showed that light consists of tiny particles that create patterns of interference just as waves do.
::爱因斯坦提出理论后,科学家们找到了支持理论的证据。 比如,双光实验显示,光是由微粒组成的,与波浪一样造成干扰模式。
Review
::回顾-
Why did scientists debate the nature of electromagnetic radiation for more than 200 years?
::为什么科学家要辩论200多年的电磁辐射的性质? -
State Einstein’s wave-particle theory of electromagnetic radiation.
::爱因斯坦的电磁辐射波粒理论。 -
What is a photon?
::什么是光子? -
After Einstein proposed his wave-particle theory, how did double-slit experiments provide evidence to support the theory?
::在爱因斯坦提出他的波粒理论后, 双光实验如何提供证据来支持这个理论?
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Electromagnetic radiation behaves like waves of energy most of the time, but sometimes it behaves like particles. From the 1600s until the early 1900s, most scientists thought that electromagnetic radiation consists either of particles or of waves but not both.
