Current or Potential Are the Input Quantity

For any output fc, if a galvanostatic regulation is considered, equation (14.16) can be written as 

The experimental arrangement devised for the transfer-function measurements involving a nonelectrical output quantity, the current or the potential being the 

Remember 14.3 Equation (14.22) provides the relationship between the usual electrochemical impedance response and the transfer function for cases where current or potential is the output. Equation (14.26) provides the corresponding relationship for cases where current or potential is the input. Equation (14.22) and equation (14.26) are distinguished by a minus sign resulting from the implicit function derivation. 

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