The study of the X-ray and its effects gave rise to the idea that there was a relation between phosphorescence and the X-rays. In 1896 Becquerel found that all the salts of uranium, both those that are phosphorescent and those that are not, emit radiations which affect the photographic plate like the X-ray and pass through thin sheets of metal. Any substance that spontaneously emits radiations like uranium is called radio-active, and is said to possess radio-activity. Besides uranium, thorium and its compounds are remarkably radio-active. Figure 1 shows the effect produced upon a photographic plate by the radiation from a piece of gas mantle which was placed upon the plate and left in the dark for five days. The gas mantle contains thorium.

Madame Curie examined many substances to determine their radio-activity, and she found that pitchblende, the mineral from which uranium is obtained, is much more radioactive than uranium. She concluded that pitchblende must contain some element more radio-active than uranium, and finally succeeded in separating from it a minute quantity, a few milligrams per ton, of salts of a new element which she called radium. Radium chloride has been obtained with a radio-activity one million times as great as that of the mineral from which it came.

rom which it came. Rutherford has found in the Becquerel rays three classes of rays: The a-rays (alpha-rays) consist of positively charged particles, having about twice the mass of the hydrogen atom, and a velocity about one tenth that of light. The B-rays (beta-rays) are negatively charged particles, having about   the mass of the hydrogen atom, and a velocity of from 0.6 to 0.96 that of light. They apparently differ from cathode rays in velocity only. The y-rays (gamma-rays) are believed to be pulses in the ether similar to the X-rays produced in a tube having a high vacuum. Of the three classes of  rays the y-rays have the greatest penetrating power and the a-rays the least. Figure 2 represents rays sent out by a radio-active  material, showing the change in direction caused by subjecting them to a strong magnetic field. The a-rays are deflected little, the B-rays much, the y-rays not at all.

اخر الاخبار

اخبار العتبة العباسية المقدسة

موكب العتبتين المقدستين يحيي ذكرى استشهاد الإمام الهادي (عليه السلام) في سامراء

العتبة العسكرية المقدسة تكرّم وفد العتبة العباسية المقدسة لمشاركته في تقديم الخدمات للزائرين

العتبة العباسية المقدسة تختتم مشاركتها في تقديم الخدمات لزائري مرقد الإمامين العسكريين (عليهما السلام)

وفد متحف الكفيل يطلع على الفنون التراثية والحرف الأصيلة في ورش مدينة أصفهان

المزيد

الآخبار الصحية

كنز غذائي على طبقك.. ماذا تفعل السبانخ بجسمك؟

ما لا يتوقعه أحد.. "سر غذائي" في الجبن الدسم

لتحسين الهضم والنوم.. هذا أفضل وقت لتناول العشاء

10 طرق بسيطة وغير مألوفة لحرق المزيد من السعرات يوميا

المزيد

الآخبار التكنلوجية

سابقة بعالم الطيران.. طائرة تقرر الهبوط بنفسها بعد ظرف طارئ

"الإنفلونزا الخارقة" تكتسح دول العالم.. وتثير قلقا كبيرا

مرحلة ما قبل الأعراض.. دواء جديد يستهدف "شرارة" الزهايمر

إزالة ثاني أكسيد الكربون من الغلاف الجوي.. ما دور المحيطات والبحار؟

المزيد

مواضيع ذات صلة

The Fluoroscope

Radiographs

The Röntgen Rays or X-Rays

Effects of the Cathode Rays

تطبيقات النانوتكنولوجي في البيئة

مصادر الإشعاع المؤين

عصر التطبيقات الطبية في مجال الاشعة

إرنست أورلاندو لورانس (1958 - 1901) Ernest Orlando Lawrence

الموجات الكهرومغناطيسية

معجلات التيار وحيد الاتجاه

الإستخدامات الحديثة للمعجلات

التشعيع بواسطة المعجلات