{"id":2481,"date":"2020-11-28T07:22:42","date_gmt":"2020-11-28T01:52:42","guid":{"rendered":"https:\/\/cbselibrary.com\/?p=2481"},"modified":"2020-11-28T11:35:42","modified_gmt":"2020-11-28T06:05:42","slug":"anode-cathode-rays-produced","status":"publish","type":"post","link":"https:\/\/cbselibrary.com\/anode-cathode-rays-produced\/","title":{"rendered":"How are the Anode and Cathode rays Produced?"},"content":{"rendered":"

How are the Anode and Cathode rays Produced?<\/strong><\/span><\/h2>\n

Atoms are made up of three subatomic particles electrons, Protons and neutrons. Electron has negative charge, proton has positive charge, whereas neutron has no charge, it is neutral. Protons and neutrons are present in a small nucleus at the centre of the atom. Electrons are outside the nucleus. The atoms of different elements differ in the number of electrons, protons and neutrons.<\/p>\n

Thermionic Emission:<\/strong><\/p>\n

    \n
  1. Thermionic emission is a process of emission of electrons from the surface of a heated metal.<\/li>\n
  2. Figure (a) shows the surface of a metal containing a large number of electrons which are free to move. The electrons are free to move at the surface but remain inside the metal.
    \n\"How<\/li>\n
  3. The electrons at the surface cannot escape because they are held back by the attractive forces of the atomic nuclei near the surface.<\/li>\n
  4. If the metal is heated to a high temperature as shown in Figure (b), some of the free electrons may gain sufficient energy to escape from the metal.<\/li>\n
  5. Electrons are more easily emitted if the metal is coated with an oxide of barium or strontium.<\/li>\n
  6. The rate of thermionic emission depends on:
    \n(a) Surface area of the metal<\/strong>
    \nThe larger the surface area, the more the number of electrons emitted.
    \n(b) Temperature of the metal<\/strong>
    \nThe higher the temperature, the more the number of electrons which will gain enough energy to escape from the metal surface.
    \n(c) Type of metal<\/strong>
    \nDifferent types of metal requires different amounts of energy for the electrons to escape.
    \n(d) Nature of the metal surface<\/strong>
    \nWhen the metal surface is coated with metal oxide, electrons can be emitted at a lower temperature.<\/li>\n<\/ol>\n

    How are the cathode rays produced?<\/strong><\/h2>\n
      \n
    1. Thermionic emission is used to produce a continuous supply of electrons. These electrons can be made to move at high speed in a vacuum tube as shown in Figure.
      \n\"How<\/li>\n
    2. The vacuum tube<\/strong> is an evacuated glass tube where streams of electrons can move without any obstruction by air molecules.<\/li>\n
    3. Inside the vacuum tube there are positive and negative electrodes. The positive electrode is called anode<\/strong> and the negative electrode is called cathode<\/strong>. When a high voltage is applied between the cathode and the anode, the electrons are accelerated at high speed from the cathode to the anode. This stream of electrons which is moving at high speed is called cathode rays.<\/li>\n<\/ol>\n

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