AJAY526:
thnx for reply.but i m totally non electronic person and i dont have meter to measure the resistance.please tell me some easy steps...here the link of video that exactlly i want to make using arduino uno
https://www.youtube.com/watch?v=dWrfEges1_E
I watched the video and followed the links. What is complicating things is that the YouTube Fritzing diagram uses an OpAmp for stability... not entirely necessary if you use the 5V from the Arduino.
Allen's schematic (attached above) is adequate for this experiment and avoids the OpAmp costs.
Ray