Discovering Radioactivity | 发现放射性

📚 Discovering Radioactivity | 发现放射性

Radioactivity is one of the most important discoveries in modern physics. This article explores how it was discovered, the nature of the radiations emitted, how they are detected, and the mathematical rules that describe decay.

放射性是现代物理学中最重要的发现之一。本文探讨它是如何被发现的、所发出辐射的性质、如何探测它们，以及描述衰变的数学规律。

1. What Radioactivity Means | 什么是放射性

Radioactivity is the spontaneous and random disintegration of unstable atomic nuclei, with the emission of ionising radiation. The process does not require any external energy input and cannot be controlled by temperature, pressure or chemical reactions.

放射性是不稳定原子核自发且随机地衰变，并发出电离辐射的过程。它不需要外界能量输入，也不受温度、压力或化学反应的控制。

In nuclear physics, an unstable nuclide is called a radioisotope. Its activity A is the number of decays per second, measured in becquerels (Bq), where 1 Bq = 1 decay per second.

在核物理中，不稳定的核素称为放射性同位素。它的活度 A 是每秒衰变次数，单位为贝克勒尔（Bq），1 Bq 等于每秒衰变 1 次。

2. Becquerel’s Accidental Discovery | 贝克勒尔的偶然发现

Radioactivity was discovered by Henri Becquerel in 1896 while studying phosphorescence. He placed uranium salts on a photographic plate wrapped in black paper and left them in a drawer. The plate darkened even without sunlight, proving that uranium emitted penetrating rays spontaneously.

1896 年，亨利·贝克勒尔在研究磷光时偶然发现了放射性。他把铀盐放在包着黑纸的照相底片上并留在抽屉里。底片在没有阳光的情况下仍然变黑，证明铀自发地发出具有穿透性的射线。

At first, Becquerel thought the rays were similar to X-rays, which had recently been discovered by Roentgen. Later work showed that the radiation came from the uranium atoms themselves, not from chemical reactions.

起初，贝克勒尔认为这种射线与伦琴新发现的 X 射线相似。后来的研究表明，辐射来自铀原子本身，而不是化学反应。

3. The Curies and New Elements | 居里夫妇与新元素

Marie and Pierre Curie used an electrometer to measure the ionising effect of uranium compounds. They found that the mineral pitchblende was more active than pure uranium, suggesting the presence of unknown radioactive elements.

玛丽和皮埃尔·居里使用静电计测量铀化合物的电离效应。他们发现沥青铀矿的放射性比纯铀更强，表明其中可能存在未知的放射性元素。

In 1898, they isolated two new elements: polonium and radium. Radium was millions of times more radioactive than uranium, and this work earned the Curies and Becquerel the 1903 Nobel Prize in Physics.

1898 年，他们分离出两种新元素：钋和镭。镭的放射性比铀强数百万倍，这项工作使居里夫妇与贝克勒尔共同获得 1903 年诺贝尔物理学奖。

4. Alpha, Beta and Gamma Radiation | α、β 和 γ 辐射

Ernest Rutherford showed that radioactive emissions could be separated by an electric or magnetic field. Alpha particles were deflected in one direction, beta particles in the opposite direction, and gamma rays were not deflected at all.

欧内斯特·卢瑟福证明，放射性辐射可以被电场或磁场分离。α 粒子向一个方向偏转，β 粒子向相反方向偏转

Published by TutorHao | A-Level Physics Revision Series | aleveler.com

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