Can current due to potential difference of earth's crust and ionosphere charge objects?

Question

A man fixes outside his house one evening a two metre high insulating slab carrying on its top a large aluminium sheet of area $m^2$ . Will he get an electric shock if he touches the metal sheet next morning?

This was a question in my textbook and the answer given is

Yes. The steady discharging current in the atmosphere charges up the aluminium sheet gradually and raises its voltage to an extent depending on the capacitance of the capacitor (formed by the sheet, slab and the ground).

I am not able to understand it, can such small current create charge in the sheet, enough to cause an electric shock?

Answer 1

I am not able to understand it, can such small current create charge in the sheet, enough to cause an electric shock?

The main problem with the example, as I see it, is they have not described what they mean by an "electric shock".

The term "electric shock" is too broad as it is often used to refer to a broad range of physiological effects of current passing through the body. Some of these effects may be harmless. Others fatal. So when using the term "electric shock" one should describe the physiological effect of concern.

That said, the event described in the question involves an electrostatic (capacitive) discharge (ESD). The magnitude and duration of current in the body will depend on the combination of capacitance, voltage, and the body impedance. Whether or not an ESD is harmful depends whether or not the magnitude and duration of potential body current exceeds the threshold for harm (e.g., ventricular fibrillation, cardiac arrests).

Information on those thresholds can be found in IEC 60479-1 (Effects of Current on Human Beings and Livestock) in table 13 and Fig 22.

Hope this helps.