Anode
Channel: 宇宙のすべての知識 プリンシピア
Date: 2019-01-17

Anode, by Wikipedia https://en.wikipedia.org/wiki?curid=2392 / CC BY SA 3.0

#Electrodes
Anode

An anode is an electrode through which the conventional current enters into a polarized electrical device. This contrasts with a cathode, an electrode through which conventional current leaves an electrical device. A common mnemonic is ACID for "anode current into device". The direction of conventional current (the flow of positive charges) in a circuit is opposite to the direction of electron flow, so (negatively charged) electrons flow out the anode into the outside circuit. In a galvanic cell, the anode is the electrode at which the oxidation reaction occurs.

An anode is also the wire or plate having excess positive charge. Consequently, anions will tend to move towards the anode.

The terms anode and cathode are not defined by the voltage polarity of electrodes but the direction of current through the electrode. An anode is an electrode through which conventional current (positive charge) flows into the device from the external circuit, while a cathode is an electrode through which conventional current flows out of the device. If the current through the electrodes reverses direction, as occurs for example in a rechargeable battery when it is being charged, the naming of the electrodes as anode and cathode is reversed.

Conventional current depends not only on the direction the charge carriers move, but also the carriers' electric charge. The currents outside the device are usually carried by electrons in a metal conductor. Since electrons have a negative charge, the direction of electron flow is opposite to the direction of conventional current. Consequently, electrons leave the device through the anode and enter the device through the cathode.

The definition of anode and cathode is slightly different for electrical devices such as diodes and vacuum tubes where the electrode naming is fixed and does not depend on the actual charge flow (current). These devices usual...