AC voltage from aluminum Grounded?

[THORPE]

My knowledge of AC voltage is very basic but I have a question.

I stumbled upon this by accident.

If you take a piece of aluminum, stick one one end into the ground just a little, say 1".

Then take a volt meter, stick one lead into the ground, the other lead anywhere on the aluminum above the ground, you get a small AC voltage reading.

It seems to have a higher reading with thicker aluminum than thin but it is a consistent reading with anywhere from .8 - 1.50 Volts AC.

Aybody know of this and what the source could be?

 

[Nik_2213]

Do you get a reading on DC ?? Do you get a reading when you put the alumini(u)m and probe into slightly salty water ? I suspect you've re-invented the electric cell...

 

[THORPE]

Haven't tried the Salty water but no reading on DC

 

[Dadface]

Hello THORPE I had the same thought as Nik but... no reading on D.C? Another thing that springs to mind is that the aluminium rod is acting like an aerial(antenna).The aluminium and its oxide layer at one of the connection points could be acting as a diode and with a meter to complete the circuit you have a simple crystal radio set.Again the problem is that there is no reading on D.C and the voltages you measure seems rather high(perhaps you could try high impedance headphones or a crystal earpiece in place of the meter).Well,I'm stumped but it's an interesting problem.

 

[sardar]

I can provide some insights into this phenomenon. It is possible for a small AC voltage to be measured when one lead of a voltmeter is placed on the ground and the other lead is placed on aluminum that is partially inserted into the ground. This is because of a process called galvanic corrosion, which occurs when two different metals are in contact with each other in the presence of an electrolyte (such as soil). In this case, the aluminum and the ground act as the two different metals, and the moisture in the soil acts as the electrolyte.

When two different metals are in contact, an electrochemical reaction can take place, resulting in a small flow of electrons between the two metals. This flow of electrons can generate a small AC voltage, which can be measured by a voltmeter. The thickness of the aluminum can affect the magnitude of the voltage because it can change the surface area of contact between the two metals.

It is also possible that the presence of other conductive materials in the soil, such as minerals or other metals, could also contribute to the AC voltage reading. Without further investigation, it is difficult to determine the exact source of the voltage.

In conclusion, the AC voltage reading observed when one lead of a voltmeter is placed on the ground and the other lead is placed on partially inserted aluminum is likely due to galvanic corrosion. Further studies and experiments could provide more information on the specific source and magnitude of the voltage.