Anode ray
Encyclopedia
Anode rays are beams of positive ion
s that are created by certain types of gas discharge tubes. They were first observed in Crookes tube
s during experiments by the German
scientist
Eugen Goldstein
, in 1886. Later work on anode rays by Wilhelm Wien
and J. J. Thomson
led to the development of mass spectrometry
.
which had a perforated cathode
. When a high electical 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 ray
s," which are streams of electron
s which move toward the cathode. Goldstein called these positive rays Kanalstrahlen, "canal rays", because they were produced by the holes or canals 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
. They were protons.
The process by which anode rays are formed in a gas discharge tube is as follows. When the high voltage is applied to the tube, its electric field
accelerates the small number of ion
s (electrically charged atom
s) always present in the gas, created by natural processes such as radioactivity. These collide with atoms of the gas, knocking electrons off of them and creating more positive ions. These ions and electrons in turn strike more atoms, creating more positive ions in a chain reaction. The positive ions are all attracted to the negative cathode, and some pass through the holes in the cathode. These are the anode rays.
By the time they reach the cathode, the ions have been accelerated to a fast enough speed that when they collide with other atoms in the gas they excite the atom's orbital electrons to a higher energy level
. When these electrons drop back to their former energy levels they release their energy as light. This light-producing process, called fluorescence
, causes the beams of ions emerging from the cathode to glow.
Canal rays are the rays that are produced by the ionization of the gas, the positive charged ions move towards the cathode and passed through the perforations of the cathode. As these perforations were named as canal so these rays are called canal rays. These are not the anode rays as these were not originated from the anode. However when cathode rays strike the anode these are highly accelerated and excite the atom's orbital electrons (of anode) to a higher energy level
. When these electrons drop back to their former energy levels they release their energy as penetrating radiations of photons, discovered by Roentegen which he named x-rays. As these rays are originated from anode these are also called anode rays.
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s that are created by certain types of gas discharge tubes. They were first observed in Crookes tube
Crookes tube
A Crookes tube is an early experimental electrical discharge tube, invented by English physicist William Crookes and others around 1869-1875, in which cathode rays, that is electrons, were discovered....
s during experiments by the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
scientist
Scientist
A scientist in a broad sense is one engaging in a systematic activity to acquire knowledge. In a more restricted sense, a scientist is an individual who uses the scientific method. The person may be an expert in one or more areas of science. This article focuses on the more restricted use of the word...
Eugen Goldstein
Eugen Goldstein
Eugen Goldstein was a German physicist. He was an early investigator of discharge tubes, the discoverer of anode rays, and is sometimes credited with the discovery of the proton.- Life :...
, in 1886. Later work on anode rays by Wilhelm Wien
Wilhelm Wien
Wilhelm Carl Werner Otto Fritz Franz Wien was a German physicist who, in 1893, used theories about heat and electromagnetism to deduce Wien's displacement law, which calculates the emission of a blackbody at any temperature from the emission at any one reference temperature.He also formulated an...
and J. J. Thomson
J. J. Thomson
Sir Joseph John "J. J." Thomson, OM, FRS was a British physicist and Nobel laureate. He is credited for the discovery of the electron and of isotopes, and the invention of the mass spectrometer...
led to the development of mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
.
Experiments
Goldstein used a gas discharge tubeGas filled tube
A gas-filled tube, also known as a discharge tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Although the envelope is typically glass, power tubes often use ceramics, and military tubes often use glass-lined metal...
which had a perforated cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
. When a high electical 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 ray
Cathode ray
Cathode rays are streams of electrons observed in vacuum tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass opposite of the negative electrode is observed to glow, due to electrons emitted from and travelling perpendicular to the cathode Cathode...
s," which are streams of electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s which move toward the cathode. Goldstein called these positive rays Kanalstrahlen, "canal rays", because they were produced by the holes or canals in the cathode. In 1907 a study of how this "ray" was deflected in a magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
, revealed that the particles
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...
making up the ray were not all the same mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
. The lightest ones, formed when there was some hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas in the tube, were calculated to be about 1840 times as massive as an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
. They were protons.
The process by which anode rays are formed in a gas discharge tube is as follows. When the high voltage is applied to the tube, its electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
accelerates the small number of ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
s (electrically charged atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s) always present in the gas, created by natural processes such as radioactivity. These collide with atoms of the gas, knocking electrons off of them and creating more positive ions. These ions and electrons in turn strike more atoms, creating more positive ions in a chain reaction. The positive ions are all attracted to the negative cathode, and some pass through the holes in the cathode. These are the anode rays.
By the time they reach the cathode, the ions have been accelerated to a fast enough speed that when they collide with other atoms in the gas they excite the atom's orbital electrons to a higher energy level
Energy level
A quantum mechanical system or particle that is bound -- that is, confined spatially—can only take on certain discrete values of energy. This contrasts with classical particles, which can have any energy. These discrete values are called energy levels...
. When these electrons drop back to their former energy levels they release their energy as light. This light-producing process, called fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
, causes the beams of ions emerging from the cathode to glow.
Canal rays are the rays that are produced by the ionization of the gas, the positive charged ions move towards the cathode and passed through the perforations of the cathode. As these perforations were named as canal so these rays are called canal rays. These are not the anode rays as these were not originated from the anode. However when cathode rays strike the anode these are highly accelerated and excite the atom's orbital electrons (of anode) to a higher energy level
Energy level
A quantum mechanical system or particle that is bound -- that is, confined spatially—can only take on certain discrete values of energy. This contrasts with classical particles, which can have any energy. These discrete values are called energy levels...
. When these electrons drop back to their former energy levels they release their energy as penetrating radiations of photons, discovered by Roentegen which he named x-rays. As these rays are originated from anode these are also called anode rays.