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Question
how did we found out the mass of positive particles in canal rays experiment with discharge tube
how did we found out the mass of positive particles in canal rays experiment with discharge tube
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Solution
Dear student,
An anode ray (also positive ray or canal ray) is a beam of positive ions that is created by certain types of gas discharge tubes. They were first observed in Crooked tubes during experiments by the German scientist Eugen Goldstein, in 1886.
Goldstein used a gas discharge tube which had a perforated cathode. When a high electrical potential of several thousand volts is applied between the cathode and anode, faint luminous "rays" are seen extending from the holes in the back of the cathode. These rays are beams of particles moving in a direction opposite to the "cathode rays" which are streams of electrons which move toward the anode. Goldstein called these positive rays Kanalstrahlen, "channel rays" or "canal rays", because they were produced by the holes or channels in the cathode. In 1907 a study of how this "ray" was deflected in a magnetic field, revealed that the particles making up the ray were not all the same mass. The lightest ones, formed when there was some hydrogen gas in the tube, were calculated to be about 1840 times as massive as an electron. As it was found the charge/mass ratio varies, the simplest atom hydrogen was used for the experiment. They found the mass of protons in this experiment. The change in mass of the electrode plate gave the mass and charge was caluculated by placing the experiment in appropriate electric field. We can also do it as follows:
One mole equals 6.022e23, just as one dozen equals 12 or one pair equals two. We can take it as a given that one mole of hydrogen atoms (not “H2” molecules) weighs 1.0079 g. Each hydrogen atom contains one proton, so one mole of protons weighs 1.0079 g. Since each mole equals 6.022× 10^23 units, we know that 6.022× 10^23 protons weigh 1.0079 grams. Dividing 1.0079 g by mole number (1.0079 / 6.022× 10^23) gives proton mass: 1.6737 × 10^-24 g.
An anode ray (also positive ray or canal ray) is a beam of positive ions that is created by certain types of gas discharge tubes. They were first observed in Crooked tubes during experiments by the German scientist Eugen Goldstein, in 1886.
Goldstein used a gas discharge tube which had a perforated cathode. When a high electrical potential of several thousand volts is applied between the cathode and anode, faint luminous "rays" are seen extending from the holes in the back of the cathode. These rays are beams of particles moving in a direction opposite to the "cathode rays" which are streams of electrons which move toward the anode. Goldstein called these positive rays Kanalstrahlen, "channel rays" or "canal rays", because they were produced by the holes or channels in the cathode. In 1907 a study of how this "ray" was deflected in a magnetic field, revealed that the particles making up the ray were not all the same mass. The lightest ones, formed when there was some hydrogen gas in the tube, were calculated to be about 1840 times as massive as an electron. As it was found the charge/mass ratio varies, the simplest atom hydrogen was used for the experiment. They found the mass of protons in this experiment. The change in mass of the electrode plate gave the mass and charge was caluculated by placing the experiment in appropriate electric field. We can also do it as follows:
One mole equals 6.022e23, just as one dozen equals 12 or one pair equals two. We can take it as a given that one mole of hydrogen atoms (not “H2” molecules) weighs 1.0079 g. Each hydrogen atom contains one proton, so one mole of protons weighs 1.0079 g. Since each mole equals 6.022× 10^23 units, we know that 6.022× 10^23 protons weigh 1.0079 grams. Dividing 1.0079 g by mole number (1.0079 / 6.022× 10^23) gives proton mass: 1.6737 × 10^-24 g.
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