Question

Can you explain what is meant by external resistance in regards to a galvanic cell? How could the external resistance lower the voltage created by the cell? Could this be a cause of why the voltage produced by the galvanic cell is lower than the theoretical voltage calculated using the Nernst equation?

Answer 1

Answer.

A electrochemistry cell (E) is an experimental device to generate electricity through a spontaneous redox reaction. Also known as Galvanic or Volta cell. When we relate the Ohm's law with a Fem E, in an electrical circuit, a generator (battery) is in charge to supply energy to the electrical charges with causes a differential in its voltage (E= I*R), which in turn produces an electrical current intensity (I = Q/t). The fem E in a circuit is defined as the generator of work done to pass inside the unit load negative terminal to the positive (E = W/Q). Moreover, the passage of electric charges inside the generator is hampered by its internal resistance (r).

If a generator with a fem E and internal resistance r is connected to an external resistor (R), we have:

I = E/(R + r)

From this equation we can conclude that Intensity will be inversely proportional to the extent of their resistance both internally and externally. The greater the External resistivity the lower the intensity. Remember, the Nernst equation allows us to calculate E in function of its concentrations ratio (Q). If Q < 1, then E is greater than E° and vice versa.