物理專業(yè)英語翻譯

1、第一章Our material world（物質(zhì)世界 ）is composed of many substances distinguished（區(qū)另1J） by theirchemical, mechanical, and electrical properties（ 特性）.They are found in nature in various physical states（ 物理狀態(tài)）-the familiar solid, liquid, and gas, along with（ 連同）the ionic "plasma "（ 等離子體 ）However, the

2、 apparent diversity（ 多樣性）of kinds and forms of material is reduced by the knowledge that there are only a little over 100 distinct chemical elements（ 元素）and that the chemical and physical features of substances depend merely on the strength of force bonds（結(jié)合）between atoms.我們的物質(zhì)世界（物質(zhì)世界）是由許多物質(zhì)（以區(qū)別區(qū)別被其

3、化工、機(jī)械、電氣性能（特性）。他們是在大自然中找到的材料在不同的物理狀態(tài)（物理狀態(tài)）一一而且熟悉的固體、液體和氣體，隨著（連同）離子“等離子體”（等離子體）然而，明顯的多樣性（多樣性）各類形式的資料將減少 知識只有一個小超過100種特定的化學(xué)元素（元素），化學(xué)和物理特征的物質(zhì)的力量僅僅看力債券（結(jié)合）之間的原子。In turn（依次）,the distinctions between the elements of nature arise from（ 起于）the numberand arrangement of basic particles（基本粒子）一electrons（ 電子），pr

4、otons（質(zhì)子），and neutrons（ 中子）.At both the atomic and nuclear levels, the structure of elements is determined by internal forces and energy（內(nèi)力和內(nèi)能 ）.1.1 FORCES AND ENERGY（力和能量）反過來（依次），區(qū)別自然元素（源自起于）電話號碼和安排基本粒子）-electrons基本粒子（電子），質(zhì)子（質(zhì)子），和中子（中子）。在兩個原子與核水平，結(jié)構(gòu)是由元素的內(nèi)力If the specific heatof iron isoC?如果的比temper

5、ature.和能量（內(nèi)力和內(nèi)能）。11力量和能量（力和能量0.45J/g oC, how much energy is required to bring 0.5kg of iron from 0oC to 100熱鐵變形、0.45J / g 需要多少能量將鐵 0.5kg從0（oC）到100（oC）嗎？*State the concept of國家溫度的概念。有何區(qū)別式What's the difference between the Celsius scale and Kelvin scale?溫標(biāo)攝氏度的規(guī)模和嗎？*Give some examples of SI units?1.

6、6 SUMMARY（概要）*Associatedwitheach basictype offorce is an energy, which may be transformed to another form for practical use.The addition ofthermal energy to a substance causes an increase in temperature, the measure of particle motion.Electromagnetic radiation arising from electrical devices, atoms

7、or nuclei may be considered as composed of waves or of photons.Matter can be converted into energy and vice versa（反之亦然）；according to Einstein's formula E = mc 2.The energy of nuclear fission is millionsof times as large as that from chemical reactions.Energy is fundamental to all of man's en

8、deavors and indeed to his survival.舉些仞子SI單位簡介（概要？ 1.6）與相關(guān)各基本類型的力量是一種力量，它可以被轉(zhuǎn)化為實(shí)際使用另一種形式的熱能。增加對某種物質(zhì)的溫度升高引起了一場的方法、質(zhì)點(diǎn)運(yùn)動。電磁輻射引起原子或核設(shè)備、電子可以被看作是由波或是的光子。物質(zhì)可以轉(zhuǎn)化為能量，反之亦然（反之亦然）;根據(jù)愛因斯坦的公式 E =mc2這些能量的核子分裂在內(nèi)也遠(yuǎn)在數(shù)百萬倍大能量從化學(xué)反應(yīng)。我們的基本人的努力，也正是為了他的性命第二章原子與原子核2.1 ATOMIC THEORY（原子理論）A complete understanding of the microsc

9、opic structure of matter （物質(zhì)微觀結(jié)構(gòu)）and the exact nature of the forces acting （ 作用力的準(zhǔn)確性質(zhì) ）is yet to （ 有待于）be realized. However, excellent models have been developed to predict behavior to an adequate degree of accuracy for most practical purposes. These models are descriptive （描述的）or mathematical often

10、 based on analogy （類推）with large-scale process, on experimental data （實(shí)驗數(shù)據(jù)），or on advanced theory.1. 對物質(zhì)的微觀結(jié)構(gòu)和作用力的準(zhǔn)確性質(zhì)的完全認(rèn)識仍有待于實(shí)現(xiàn)。然而，為了實(shí)際的用途，能足夠精確地預(yù)知物質(zhì)在微觀世界行為的模型已經(jīng)被研究出來。這些模型是描述性的或數(shù)學(xué)的，基于對大尺度過程的類推、實(shí)驗數(shù)據(jù) 或先進(jìn)的理論。The most elementary concept （元素概念）is that matter is composed of individual particles （單個粒子）一a

11、toms -that retain their identity （同一性, 特性）as elements in ordinary physical and chemical interactions. Thusa collection of helium atoms （ 氮原子）that forms a gas has a total weight that is the sum of the weights of the individual atoms. Also, when two elements combine （ 結(jié)合）to form a compound （化合物）（e.g.,

12、 if carbon atoms （ 碳 原子）combine with oxygen atoms （ 氧原子）to form carbon monoxide molecules （一氧化碳分子）,the total weightof the new substance is the sum of the origin elements.2. 公認(rèn)的物質(zhì)的概念是：物質(zhì)是由單個粒子一一原子組成，在普通的化學(xué)和物理反應(yīng)中原子保持了元素的特性。因此，因此一團(tuán)由氯原子組成的氣體的重量就是其中每一個原子重量的總和。同樣，當(dāng)兩種元素結(jié)合成化合物時（例 如：碳原子與氧原子結(jié)合成一氧化碳分子。），新物質(zhì)的總重

13、量是原先的元素的質(zhì)量之和。There are more than l00 known elements. Each is given an atomic number （原子序數(shù) ）in the periodic table ofthe elements （ 元素周期表）-examples are hydrogen （H） l, helium （He） 2, oxygen （O） 8, and uranium （U） 92. The symbol Z is given to the atomic number, which is also the number of electrons in

14、the atom and determines its chemical properties （性質(zhì)）.The atomic weight （ 原子質(zhì)量）Mis the weight in grams of a definite （ 明確的）number of atoms, 6.0210 23 ,which is A vogadro' s number （阿佛伽德羅常數(shù)）,N）.3. 有超過100種的已知元素。每種元素在元素周期表中都有一個給定的原子序數(shù)。例如氫（H） 1,氯（He） 2,氧（O） 8以及鈾（U） 92。符號Z表示原子序數(shù)，這也正是決定著原子化學(xué)性質(zhì)的原子中電子的數(shù)目

15、。 原子量M （單位：克）是6.021023個原子的質(zhì)量之和。6.021023就是阿佛伽德羅常數(shù)，用N來表示。We can easily find the number of atoms per cubic centimeter N每立方厘米 ）in a substance if its densityri;a Min grams per cubic centimeter is known. This procedure （程序, 手續(xù)）can be expressed as a convenient （便禾U的）formula for finding N the number per cub

16、ic centimeter for any material如果每立方厘米內(nèi)的物質(zhì)密度已知，我們就可以很容易地求出每立方厘米中原子的個數(shù)。任何物質(zhì)中每立方厘米的 原子數(shù)都法可以方便的用這個公式算出O2.2 GASES （氣體）氣態(tài)）are described approximately by the perfect gas law 理想氣體規(guī)律（方Substances in the gaseous state （絕對溫度），pV=nkT.）, relating pressure, volume, and absolute temperature （An increase in the temp

17、erature of the gas due to heating causes greater molecular motion, which results inan increase of particle bombardment （n炮擊； 轟擊 ）of a container wall and thus of pressure on the wall.The particles of gas, each of mass m have a variety of（多種的）speeds v in accord with 與致 Ma<well ' sgas theory （麥克

18、斯韋氣體理論）as shown in Fig. 2.1.4. 氣態(tài)的物質(zhì)可以用與壓力、體積和絕對溫度有關(guān)的理想氣體規(guī)律方程pV=nkT來近似地描述。溫度上升將引起分子運(yùn)動的加劇一一從而引起粒子對容器內(nèi)壁的碰才a的增加而導(dǎo)致其壓力的增大。每種質(zhì)量（m>的氣體粒子具有的不同速度與圖2.1所示的麥克斯韋理論一致。The most probable speed（ 最概然速率），at the peak of Maxwellian distribution （麥克斯韋分布）,is dependenton temperature according to the relation （關(guān)系式）The k

19、inetic theory of gas （ 氣體動力學(xué) ）provides a basis for calculating properties such as the specific heat （比熱）.Using the fact from Chapter l that the average energy of gas molecules is proportional （成比例的）to thetemperature, e，we3can deduce （推想）,that the specific heat of a gas consisting only of atomsis c S

20、phere2 mis the mass of one atom.卷從麥克斯韋分布圖上可以看到，在其峰值處出現(xiàn)的氣體粒子的最概然速率，按照這個關(guān)系式，是與溫度緊密相關(guān)的。氣體動力學(xué)為計算諸如比熱之類的一些性質(zhì)提供了基礎(chǔ)。用第一章中氣體分子的平均能量正比于溫度的 事實(shí)，E 3kT ,我們可以推斷出單元子氣體的比熱c 3ki；nT在公式中m是一個原子的質(zhì)量。2.3 THE ATOM AND LIGHT（原子與光）2Until the 20th century the internalstructure of atoms was unknown, but it was believed that el

21、ectric charge（電荷）and mass were uniform （統(tǒng)的）. Rutherfor performed （執(zhí)行）some crucial（至關(guān)緊要的）experiments in whichgold atoms were bombarded by charged particles. He deduced （推斷）in 1911 that most of the mass and positive charge （正電荷） of an atom were concentrated （ 集中的）in a nucleus of radius only about l0-5

22、 times that of the atom,and thus occupying a volume of about 10-l5 times that of the atom. The new view of atoms paved the way for （為鋪平道路）Bohr to find an explanation for the production of light.6. 直到20世紀(jì)，原子的內(nèi)部結(jié)構(gòu)仍然是未知的，但是人們確信核電荷數(shù)與原子質(zhì)量是相同的。盧瑟福進(jìn)行了一些重要的實(shí)驗，包括用帶電粒子轟擊金原子。他在 1911年推斷出：原子的質(zhì)量和正電荷都集中在半徑為 l05分之一

23、 的原子核，占原子體積的10 l5分之一。關(guān)于原子的新觀點(diǎn)為波爾解釋光的產(chǎn)生鋪平了道路。The measured （有規(guī)貝U的）distribution of lightamong the different wavelengths （波長）at a certain temperaturecan be explained by the assumption （ 假設(shè)）that light is in the form of photons. These are absorbed and emitted with definite （定的）amounts of energy Ethat are

24、proportional to the frequency , according toE = hv, whereh is Planck' s constant , 6.63 x l0 -34 J-sec. For examp1e, the energy corresponding to（ 相當(dāng)于）a frequency of 5.l x l0 14 is （6.63 xl0-34） （5.l X1014） = 3.4 x l0 -19 J, which is seen to be a very minute （ 微小的）amount of energy.7. 在一定溫度不同波長光的有

25、規(guī)則分布可以用光是光子形式存在的假設(shè)來解釋。這要吸收或者放出一定數(shù)量的能量E,根據(jù)公式 E = hv（這里的h表示普朗克常量 6.63 x l0 -34 J-sec ）,能量與頻率成正比。例如：頻率為 5.lXl0 14的光的能量相當(dāng)于（6.63 X l0-34） X（5.l X1014） = 3.4 Xl0-19 J ,這通常被看做是非常微小的能量。He（Bohr） assumed that the atom consists of a single electron moving at constant speed in a circular orbit about a nucleus -

26、the proton-as sketched in Fig. 2.2. Each particle has an electric charge of l.6 x l0-l9 coulombs, but the proton has a mass that is 1836 times that of the electron. （Figure 2.2 ）8. 波爾假設(shè)（氫）原子由一個單獨(dú)的電子繞著一個核子一一質(zhì)子，以圓形軌道作恒定速度的移動一一見圖2.2 ,每個粒子有l(wèi).6 Xl0-l9庫倫的電量，質(zhì)子的質(zhì)量是電子質(zhì)量的1836倍。The energy of the photon hv is

27、equal to the difference between energies in the two orbits. The smallest orbit has a radius R = 0.53 x l0 -l0 m, while the others have radii increasing as the square （ 平方）of integers （calledquantum numbers （ 量子數(shù)）.Thus if n is l, 2, 3, . . . , the radius of thenth orbit is R = n2R .9. 光子的能量hv等于兩個軌道能量

28、之差。最小軌道半徑為 R = 0.53 Xl0-l° m,其它軌道半徑隨著整數(shù)的平 方（量子數(shù)）增長。因此，如果 n是1、2、3，那么第n層軌道半徑應(yīng)為 R = n2R 。The energy of the atom system when the electron is in the first orbit is曰=-l3.5 eV, where the negativesign （負(fù)號）means that energy must be supplied to remove the electron to a great distance and leave the hydrog

29、en as a positive ion （ 陽離子）.The energy when the electron is in thenth orbit is E = E 1/n 2. The various discrete（不連續(xù)的）levels are sketched （ 繪圖）in Fig. 2.4.10. 當(dāng)電子在第一個軌道時，原子系統(tǒng)的能量為E1 = -l3.5 eV ,負(fù)號表示把電子移到一個較遠(yuǎn)的距離只剩下陽離子時外界必須提供的能量。電子處于 n軌道時，能量為 E = E 1/n2,各種不連續(xù)的等級見圖2.4 。The electronic structure of the ot

30、her elements is described by the shell model （ 殼模型）,in which a limited number of electrons can occupy a given orbit or shell. The atomic number Z is unique （ 獨(dú)特的）for each chemicalelement, and represents （描繪）both the number of positive charges on the central massive （結(jié)實(shí)的）nucleus ofthe atom and the nu

31、mber of electrons in orbits around the nucleus.The chemical behavior of elements is determined by the number of electrons in the outermost （最夕卜面的）orvalence （ 原子價）shell.11. 其它元素的電子模型是用殼模型來描述的，一定限制數(shù)量的電子能夠占據(jù)一個給定的軌道或殼層。對每一個化學(xué)元素，原子序數(shù)Z是唯一的，它代表了原子中央結(jié)實(shí)核子的正電荷數(shù)以及圍繞核子的軌道的電子數(shù)。最外層的電子數(shù)或化合價層，決定了元素的化學(xué)性質(zhì)。2.4 LASER B

32、EAMS（激光束）Ordinary light as in the visible range （可見區(qū)）is a mixture of many frequencies, directions,and phases（狀態(tài)）.In contrast, light from a laser （ "Light Amplification by Stimulated Emission of Radiation " ） consists of a direct beam of one color and with the waves in step （相干）.Lasers can

33、be constructed from several materials. The original one （I960） was the crystalline gem ruby （水晶紅寶石 ）.Others use gases such as a helium-neon（氮-短）mixture, or liquids with dye in them, orsemiconductors（半導(dǎo)體）.Lasers are widely used where an intense （ 強(qiáng)烈的）well-directed beam is required, as in metal cuttin

34、g and welding, eye surgery （ 眼部夕卜科手術(shù) ）and other medical applications, and accurate surveying and range finding（ 精確的測量和測距 ）.Newer applications are noise-free phonographs （無噪聲留聲機(jī) , 電唱機(jī)），holograms （全息攝影 ）（3D images）, and communication between airplane and submarine （潛水艇）.12. 普通光，例如可見光區(qū)，是由許多頻率、方向和狀態(tài)不同的光

35、混合而成的。相對的是，激光是由同一方向的單一顏色的光束組成，而且是相干波。激光的產(chǎn)生可以來源于多種材料。最早的一種是 1960年使用的水晶紅寶石。其 它的還可以用氣體（如氮-短混合氣體），或者染料液體，以及半導(dǎo)體來做激光發(fā)生器。激光可以被廣泛地應(yīng)用于需要 良好方向性光/熱束的地方，例如金屬的切割與焊接，眼部外科手術(shù)及它醫(yī)療應(yīng)用還有精確的測量和測距上。新出現(xiàn)的 應(yīng)用還包括無噪聲留聲機(jī)、全息攝影以及飛機(jī)和潛艇的通訊。Most elements are composed of particles of different weight, called isotopes （同位素）.For insta

36、nce, hydrogen has three isotopes of weights in proportion l, 2, and 3 -ordinary hydrogen, heavy hydrogen （deuterium ）, andtritium（ M）.The nucleus of ordinary hydrogen is the positively charged proton（帶正電的質(zhì)子）;the deuteron（笊核）consists of a proton plus a neutron, a neutral particle（中性粒子）of weight very

37、close to that of the proton; the triton（ M核）contains a proton plus two neutrons.13. 大多數(shù)元素是由重量不同的粒子構(gòu)成，我們稱之為“同位素”。例如：氫元素有三種同位素，原子量比為1：2： 3普通氫 O、重氫（笊）以及超重氫（笳）o普通氫的原子核是一個帶正電的質(zhì)子；笊核由一個質(zhì)子加一個重量十分接近質(zhì)子的中性粒子（中子）組成；笳核則是由一個質(zhì)子加兩個中子組成。1.6 SIZES AND MASSES OF NUCLEI （核的大小和質(zhì)量）The dimensions （ 尺寸）of nuclei （nucleus 的

38、復(fù)數(shù)）are found to be very much smaller than those of atoms. Since the proton weight is much larger than the electron weight, thenucleus is extremely dense. The nucleiof other isotopes may be viewed as closely packed particles of matter-neutrons and protons-forming a sphere whose量為1.007277 ,中子的為1.00866

39、5 ,兩者相差只有大約 0.1%。在這種比例下電子的質(zhì)量為 0.000549。The atomic mass unit （amu）（原子質(zhì)量單位 ），as 1/12 the mass of12C, corresponds to （ 相應(yīng)于）an actual massof 1.66 l0 -24 g. To verify （ 校驗）this, merely divide l g by Avogadro ' s number 6.02 l0 23. It is easy to show that 1 amu is also equivalent to 931 MeV. We calcul

40、ate the actual masses of atoms and nuclei by multiplying （乘）the mass in atomic mass units by the mass of 1 amu.15. 原子質(zhì)量單位amu表示一個12C原子質(zhì)量的1/12,相應(yīng)于實(shí)際的質(zhì)量是l.66 l0 -24克。要校驗這個值，只 需用1克除以阿伏伽德羅常數(shù) 6.02 l0 the nucleons are very close to each other, and binds them into a compact structure （緊湊結(jié)構(gòu)）.Associated witht

41、he net force is a potential energy of binding（結(jié)合勢能）. 同種電荷之間的靜電斥力隨著它們距離的平方成反比變化，可以想見其會大到核子無法形成的地步。我們可以憑經(jīng)驗推斷出一一核力的作用范圍一定非常短的。只有當(dāng)核子之間靠得很近時，核力才起作用將它們緊密地結(jié)合在 一起。與這種合力相關(guān)的是結(jié)合勢能。To disrupt （ 使分裂）a nucleus and separate it into its component （ 組成的）nucleons, energy must be supplied from the outside. Recalling E

42、instein's relation between mass and energy, this is the same as saying that a given nucleus is lighter than the sum of its separate nucleons, the difference being the binding mass-energy. Let the mass of an atom including nucleus and external electrons beMand letmn and mH be the masses of the ne

43、utronand the proton plus matching electron （匹配電子）.Then the binding energy isB = total mass of separate particles - mass of the atom orB = Nm + Z mH- M. 要想把一個原子核分裂成組成它的核子，必須從外部給它一定的能量?；叵霅垡蛩固官|(zhì)能方程，也可以換個 說法：一個的原子核要比組成它的所有核子的質(zhì)量之和要輕，而這個差值就是其結(jié)合能。CHAPTER 3 Radioactivity（放射性） 里 Many naturally occurring and m

44、an-made isotopes have the property of radioactivity（放身寸性）， whichis the spontaneous（ 自發(fā)的）disintegration （decay）（ 衰變）of the nucleus with the emission of a particle.The process takes place in minerals （ 礦物質(zhì)）of the ground, in fibers （ 纖維）of plants, in tissues（ 組 織）of animals, and in the air and water, a

45、ll of which contain traces （ 痕跡,微量）of radioactive elements. 1、許多天然和人造同位素都具有放射性，這是核子發(fā)射出粒子的自發(fā)衰變。這個過程發(fā)生在地表的礦物中、植物的纖 維中、動物的組織中、空氣和水中，所有的一切都存在著放射性元素的痕跡（放射性元素?zé)o處不在）。3.1 RADIOACTIVE DECAY （放射性衰變） 廿 Many elements that are found in nature or man-made are radioactive（放射f的 ）,emitting alphapartic1es（ ）, beta par

46、ticles （） （including electron or negatron and positron）, neutrinos（中微子）,andgamma rays（ ）. Some examples are as following:2、許多天然和人造的元素都具有放射性，能發(fā)射阿爾法 （）粒子、貝塔（）粒子（包括電子或者負(fù)電子和正電子）、中 微子和伽馬（）射線。舉例如下：3.2 THE DECAY LAW（衰變規(guī)律） n The rate at which a radioactive substance disintegrates （and thus the rate of relea

47、se of particles） depends on the isotopic species（種類，核素）,but there is a definite （定的）“decay law“ that governs（管理,支配）the process. In a given time period, say one second, each nucleus of a given isotopic species has the same chance of decay. If we were able to watch one nucleus, it might decay in the n

48、ext instant （立即 的）,or a few days later, or even hundreds of years later. o很明顯：1 amu也相當(dāng)于931兆電子伏（E = mc 2）。我們可以用原子質(zhì)量 乘以每一原子質(zhì)量單位的質(zhì)量來計算原子和核子的確切質(zhì)量。1.7 BINDING ENERGY（結(jié)合能）The force of electrostatic repulsion （靜電排斥）between like charges （同種電荷），which varies inversely （相 反地）as the square of their separation,

49、would be expected to be so large nuclei could not be formed. The fact that they do exist is evidence （ 證明）there is an even larger force of attraction. The nuclear force （核力）isof very short range, as we can deduce from（從一推論出）the above rule of thumb. The nuclear force acts only when3、放射性物質(zhì)的衰變率（粒子釋放率）決

50、定于同位素的種類，但是也確定存在著“衰變規(guī)律”支配著這個過程。在一它可能個給定的時間段，譬如一秒，給定同位素的每個核子都具有相同的衰變幾率。如果我們能對某個核子進(jìn)行觀察的話, 在下一個瞬間發(fā)生衰變，也有可能在幾天甚至幾百年以后才發(fā)生衰變。SU Such statistical統(tǒng)計學(xué)的 ）behavior is described by a constant property of the atom calledhalf-life （ 半衰期）.This time interval（ 間隔），symbolized by t h is the time required for half of t

51、he nuclei to decay, leaving half of them intact（完整無缺的 ）.We should like to know how many nuclei of a radioactivespecies remain at any time. If we start at time zero with N0 nuclei, after a length of time th there willbe No/2; by the time 2t h has elapsed （ 流逝），there will be No/4; etc. A graph of the

52、number of nuclei as afunction of time is shown in Fig. 3.l.tH表示的時間間隔指的是一半的核子發(fā)N個核子，那么經(jīng)過了 tH的時間以后,4、這種統(tǒng)計學(xué)上的表現(xiàn)可以用原子的一個恒定屬性一一半衰期來表示。這個用 生衰變所需要的時間。我們想知道在任意時間放射性核素的剩余量。如果在一開始有核子還剩下N/2個；經(jīng)過2tH時，核子還剩下 N/4個核子數(shù)與時間的函數(shù)關(guān)系可以用圖3.l來表示二 For any time t on the curve （曲線圖），the ratio of the number of nuclei present to th

53、e initial computed. It is proportional to the rates of emission of particles or rays from the sample and thus to the activity A of the source. The process is repeated after an elapsed time for decay. The resulting values of activity are plotted on semi-log graph paper （半對數(shù)坐標(biāo)紙）as in Fig. 3.3, and a s

54、traight line drawn through the observed points. From any pairs of points on the line and t h = 0.693/ can be calculated （see Exercise 3-8）.（初始的N加Half-lives range from very small fractions （）numberist t1tH2小部分, 片斷）of a second to billions of （given數(shù)十億）years, withbyeach radioactive isotope （ 放射性同位素 ）ha

55、ving a definite half-life.5、曲線上任一時刻t ,當(dāng)前的核子數(shù)與初始的核子數(shù)的比率如下式表示：半衰期從零點(diǎn)幾秒到數(shù)十億年不等，每種放射性同位素都有一個確定的半衰期。No口 The formula for N/N。is notvery convenient for calculationsexcept when t is some integer multipleof t h. Defining the decay constant equivalent （ 同 意 義 的We find that = 0.693/t h6、N/N。這個公式并十分便于計算，除非（lamb

56、da）, as the chance of decay of a given nucleus each second, an） exponential （ 指 數(shù) N勺） t formula for decayeNot是tH的整數(shù)倍。衰變常數(shù)的定義是：一個原子核在單位時間內(nèi)發(fā)生衰變的is幾率，可以得到一個意義相同的指數(shù)方程:我們可以得出 =0.693/t h 0N t一 eNo The number of disintegrations per second （dis/sec） of a radioisotope is called the activity, A.Since the deca

57、y constantis the chance of decay each second of one nucleus, for N nuclei the activityis the product （ 乘積）A = N.The unit dis/sec is called the becquerel （Bq）, honoring the scientist whodiscovered radioactivity （ 放射性活度）.Another older and commonly used unit of activity is the curie （Ci）named after the

58、 French scientists Pierre and Marie Curie who studied radium （If）. The curie is 3.71010dis/sec, which is an early measured value of the activity per gram of radium.7、放射性同位素每秒衰變的原子數(shù)稱為活度（記作A）。既然衰變常數(shù) 是核子每秒衰變的幾率，N個核子的活度是乘積慶=單位dis/sec稱為“貝克勒爾” （Bq）,用來紀(jì)念這位發(fā)現(xiàn)放射性活度的科學(xué)家。另一個更早的曾被普遍使用的 放射性活度的單位是“居里” （Ci）,這是以研究鐳的法國科學(xué)家皮埃爾和瑪麗居里的名字命名的。1居