Could Grove GSR sensor board could be used to measure brainwaves? Yes I know this is used to measure skin resistance not current but I think (correct me if I am wrong) from Ohm Law, also I saw Grove GSR has op-amps so I think it could amplify electric signal made by brain
No, it only can measure skin conductance. Not brainwave.
Could I ask why? If I use other sensors that default connected to certain places on head and ears. EEG measures current made by brain and transported on skin. Knowing Ohm Law (V = IR) we could in theory calculate voltage. If there is mistake in my text I would be happy to learn something new 
Also
I connected two cables with pins to the board instead of sensors and put them in this points on forhead, and to compare in hand, legs etc. '
In hands readings were 200 - 300 but on the forhead results was near 0 or < 200 sometimes from 1 to 20. My forhead weren't sweaty
This is my setup the purple cable is positive and is on left side and yellow is negative and it is on right side.
When I put this setup like this on the forhead it shows lues from 0 to 200 but when I am touching it with my hand values are from 300 - 500
Also my friend is arguing that the output is voltage so I shouldn't worry about any calculations
EDIT:
In the future I would use professional electrodes if this theory would be a truth
I put micrometer (V-DC) to my forhead in those points and it detected something and I wonder if this is just an error or my assumptions are wrong or there is something in my way of thinking
I just wanna now if I made mistake in my thinking an I should try other approach or I am right that using this board with other sensors (here represented by purple and yellow cables) could amplify this electric signalon my scalp enough so it could be "used"
I promise I'll stop making this posts but I don't want to waste my time for something that wouldn't work
Did you read Post #2?
A deluge of randomness does not disprove a fact.
See post #4.
Did you happen to move while wearing it?
Yes it can but only by a factor of 2. That is not enough to see an EEG signal with an arduino.
What you are seeing is just noise and electromagnetic radiation picked up by the wires and your head.
- Post 2 is answear no because of no, no explenation why it wouldn't work
- It's contradicts with post #2 he says that Grove GSR measure conductivity and there is in specification that input is resistance and there is caution that Grove GSR measure resistance NOT conductivity and according to Ohm Law V = IR as I checked it, and also as I checked EEG measurment is measuring voltage on certain points of the skin of the head so I assumed that if instead of connecting standard electrodes I'll connect electrodes to measure it instead of connecting electrodes for measuring GSR on fingers I could try to do this and this is my question about
- No
I see, I thought it was good to ask, I saw that this project is bit similar to the amplificator from OpenEEG project so I thought it could work
It's similiar just not enough gain. The open EEG amplifier has a nominal gain of 7812 and can be adjusted up to 19000.
Rather verbose for a "no."
Any other questions?