Microdisc vs Planar Electrode

Consider a microdisc electrode of radius re = 1 fxm under steady-state conditions for the electrolysis of a species of bulk concentration c and diffusion coefficient 

If the same system were electrolysed at a large planar electrode under diffusion-controlled conditions, at what time after the start of electrolysis would the same average flux be observed on the planar electrode as at steady state on the microdisc 

The steady-state diffusion-controlled current at the microdisc electrode is given by 

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