Anode

An anode is an electrode through which electric current flows //into// a polarized electrical device. The direction of electric current is, by convention, opposite to the direction of electron flow. In other words, the electrons flow from the anode into, for example, an electrical current. Mnemonic: ACID (Anode Current Into Device). A widespread misconception is that anode polarity is always positive (+). This is often incorrectly inferred from the correct fact that in all electrochemical devices negatively charged anions move towards the anode (hence their name) and positively charged cations move away from it. In fact anode polarity depends on the device type, and sometimes even in which mode it operates, as per the above electric current direction-based universal definition. Consequently, as can be seen from the following examples, in a device which consumes power the anode is positive, and a device which provides power the anode is negative:
 * ** In a discharging battery or galvanic cell (diagram at right) the anode is the negative terminal since that is where the current flows into the device (see drawing). This inward current is carried externally by electrons moving outwards, negative charge moving one way constituting positive current flowing the other way. It is continued internally by positive ions flowing into the electrolyte from the anode, i.e., away (surprisingly) from the more negative electrode and towards the more positive one (chemical energy is responsible for this "uphill" motion).
 * In a recharging battery, or an electrolytic cell electrolytic cell, the anode is the positive terminal, which receives current from an external generator. The current through a recharging battery is opposite to the direction of current during discharge; In other words, the electrode which was the cathode during battery discharge becomes the anode while the battery is recharging.
 * In a cathode ray tube, it is the positive terminal where electrons flow out of the device, i.e., where positive electric current flows in.
 * [[image:http://t2.gstatic.com/images?q=tbn:ANd9GcT6Ag7r2kBlYLSlldpzh1qXvtEjpBp5v6JtYd_FsmwP1Q9TX6s7mg width="176" height="225"]][[image:http://t1.gstatic.com/images?q=tbn:ANd9GcTKm22YocfDYZp0bQnztbeUmtmBEUvASOnVHCsukDy0CdBF9BhK width="192" height="263"]]

How to Define Anode and Cathode
Defintion: the anode of a device is the terminal where current flows in from the outside. The cathode of a device is the terminalwhere currents flows out. This is illustrated in the figure below: As always, electrons flowing in is the same as posotive current flowing out, and vice versa

Anodes and Cathodes are found in batteries.

__Galvanic Cell Anode and the Flow of Elections__

The flow of electrons is always from anode to cathode outside of the cell or device. Because this is the only way that a current would be able to transfer out of the cell(s). With the exception of diodes, where electrode naming always assumes current in the forward direction. Electrons flow in the opposite direction, even when the diode reverse-conducts either by accident. The anode is the negative electrode from which electrons flow out towards the external part of the circuit. Internally the positively charged cations are flowing away from the anode (even though it is negative and therefore would be expected to attract them, this is due to electrode potential r elative to the electrolyte solution being different for the anode and cathode metal/electrolyte systems). External to the cell in the circuit, electrons are being pushed out through the negative contact and thus through the circuit by the voltage potential as would be expected. In the United States, many battery manufacturers regard the positive electrode as the anode, particularly in their technical literature. Though technically incorrect, it does resolve the problem of which electrode is the anode in a secondary (or rechargeable) cell. Using the traditional definition, the anode switches ends between charge and discharge cycles.