Hi all
This sounds like an easy query but its deceptive and I've seen this question come
up on several other forums and caused quite a debate among people of all science
knowledge levels. To the extent that I have yet to see an answer that truly made sense....
It is commonly known that when cells are in series, the voltages are added to make the combined total. But why exactly is this?Lets say you have 3 x 1.5 V dry cells stacked anode to cathode as expected. This as we
know will provide a combined potential difference of 4.5 V.
When dealing with a single cell, the situation is relatively simple - electrons flow from the
anode (eg zinc) to the cathode (via wire) where they pass through the metal (copper/brass) cap and into the carbon electrode inside the cell. The de-energised electrons in the electrode then react with the surrounding electrolytic paste inside the cell in order to avoid the build up of negative charge (which would prevent further flow of current) and to avoid the increase of pressure that would occur due to the formation of gaseous species (typically ammonia and hydrogen).
How does this work when dealing with multiple cells?For there to be a combined 4.5 V this must mean that each coulomb of charge leaving the
anode now has 3x the energy as it did before (4.5 V = 4.5 J / 1 C).
But how does this voltage build up from the top cell's anode to the bottom cell's anode which is connected to the conducting wire? As the cells are in series each anode is in direct
contact with a cathode (apart from the last one), but how do the energised electrons pass
through each cell in order to build up the voltage? They cant pass through the carbon
electrode because they would react with positively charged species such as NH4+ in the
surrounding electrolytic paste and also the carbon electrode isn't in direct contact with both
the cathode and anode.
I've posted this question in the physics forum as well to double my chances!