Measuring on A/C with a digital voltmeter:
Measurement One I connect the ground lead to earth on a 3-prong plug, And hold the other lead with my thumb and forefinger, And observe that I register approximately 53 +/ 2 mV. In this configuration I conclude that my body electrical potential compared to ground is about 53 mV.
Measurement Two Same as above, but now my body is also grounded to earth. I now observe that I register 1 +/ 1 mV. In this configuration I conclude that my body electrical potential is about the same as earth.
Measurement Three I measure my body vs. ground with a hand on my Macbook Pro with aluminum case and connected to power through a 3 prong outlet. I observe 38 +/ 2 mV.
Measurement Four Macbook case vs. ground yields 5 +/- 1 mV.
Hypothesis: I had thought that by touching my MacBook Pro, my body would have the earth voltage (basically something like 2-5 mV).
Instead, even though the case is sitting at 5 mV, when I touch it, my body voltage (53 mV) drops to only 38 mV instead of the hypothesized 2-5 mV.
Why is this happening?
And is my experiment any good to begin with? I had hypothesized that working on my Macbook was equivalent to touching the grounding strip at removing voltage across my body. This seems to not be true.
Thank you in advance for any insight and education.