(+/-) signs of electronic devices, and anode/cathode notations seem to be ever-embarrassing. This post is intended to offer a solid understanding to quench further annoyance on this matter.
1. The directions are in opposite
1.1 Current flows from (+) to (-)
: This is just convention, and it is virtual.
It is different from the truth but is accepted and dominant.
1.2 Electrons flow from (-) to (+)
: This tells the truth as the movement of electrons brings the current flow.
1.3 Conclusion
: (+/-) signs are easy to apply in our life;
as we learn that the current flows from (+) to (-) anyway.
And this concept is also accepted in Electronics, and Electric Eng.
2. In Material science
2.1 Cathode/Anode notation is more accurate
2.2 Cathode
*Circuit is noted as the metallic connection between 2 electrodes.
: Cathode is the electrode which pushes holes(+) to the circuit.
Spontaneously, pulls electrons(-) from the circuit.
: The exact definition of cathode is, where the reduction occurs
as electrons are pulled via circuit.
2.3 Anode
: Anode is the electrode which pushes electrons(-) to the circuit.
Spontaneously, pulls holes(+) from the circuit.
: The exact definition of anode is, where the oxidization(== oxidation) occurs
as electrons are pushed toward circuit.
2.4 Conclusion
: Cathode pushes holes to the circuit (+ sign)
Anode pushes electrons to the circuit (- sign)
: As there should be ionic exchange inside the battery cell,
electrons collected to Cathode, again released as anion
through salt bridge (Galvanic cells).
You might make use of the .ppt that I have made for this posting.
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