Search results
Results From The WOW.Com Content Network
Diagram of a copper cathode in a galvanic cell (e.g., a battery). Positively charged cations move towards the cathode allowing a positive current i to flow out of the cathode. A cathode is the electrode from which a conventional current leaves a polarized electrical device such as a lead-acid battery.
The terms anode and cathode are not defined by the voltage polarity of electrodes, but are usually defined by the direction of current through the electrode. An anode usually is the electrode of a device through which conventional current (positive charge) flows into the device from an external circuit, while a cathode usually is the electrode through which conventional current flows out of ...
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 sufficient speed such that when they collide with other atoms or molecules in the gas they excite the species to a higher energy level. In ...
In the early experimental cold cathode vacuum tubes in which cathode rays were discovered, called Crookes tubes, this was done by using a high electrical potential of thousands of volts between the anode and the cathode to ionize the residual gas atoms in the tube. The positive ions were accelerated by the electric field toward the cathode, and ...
SOFCs are unique because negatively charged oxygen ions travel from the cathode (positive side of the fuel cell) to the anode (negative side of the fuel cell) instead of protons travelling vice versa (i.e., from the anode to the cathode), as is the case in all other types of fuel cells. Oxygen gas is fed through the cathode, where it absorbs ...
The alternating voltage to be rectified is applied between the cathode and the plate. When the plate voltage is positive with respect to the cathode, the plate electrostatically attracts the electrons from the cathode, so a current of electrons flows through the tube from cathode to plate. When the plate voltage is negative with respect to the ...
A side effect of improperly applied cathodic protection is the production of atomic hydrogen, [63] leading to its absorption in the protected metal and subsequent hydrogen embrittlement of welds and materials with high hardness. Under normal conditions, the atomic hydrogen will combine at the metal surface to create hydrogen gas, which cannot ...
The cathode may be surrounded by a shield to prevent sputtering. [226] [227] The cathode is a layer of barium oxide which is coated on a piece of nickel for electrical and mechanical support. [228] [143] The barium oxide must be activated by heating to enable it to release electrons. Activation is necessary because barium oxide is not stable in ...