In a cathode ray tube, it is the positive terminal where electrons flow out, i.e., where current flows in.Īn electrode through which current flows the other way (out) is a cathode.Note electrode naming for diodes is always based on the direction of the forward current (that of the arrow, in which the current flows 'most easily'), even for types such as zener diodes or solar cells where the current of interest is the reverse current. In a diode, it is the positive terminal at the tail of the arrow symbol, where current flows into the device.In a recharging battery, or an electrolytic cell, the anode is the positive terminal, which receives current from an external generator.If the anode is composed of a metal, electrons which it gives up to the external circuit must be accompanied by metal atoms missing those electrions (cations) moving away from the electrode and into the electrolyte. At the anode, the current is continued internally by positive ions ( cations) moving 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). Since this inwards current is carried externally by electrons moving outwards, the negative charge moving one way amounts to positive current flowing the other way. In a discharging battery or galvanic cell (drawing) the anode is the negative terminal, where conventional current flows in, and electrons out.To dispel a common misconception, often incorrectly inferred from the correct fact that in all electrochemical devices negatively charged anions move towards the anode and/or positively charged cations move away from it, anode polarity is not always positive but depends on the device type, and sometimes even in which mode it operates, as determined by the above current direction-based universal definition. Electrons flow in the opposite direction to the positive electric current. Mnemonic: ACID (Anode Current Into Device). File:Zinc anode.png Diagram of a zinc anode in a galvanic cell.Īn anode is an electrode through which (positive) electric current flows into a polarized electrical device.

Anode cathode mnemonic