Answer:
When you place your hand on a conductive paper while taking a measurement it changes the magnetic field and line of force of the point charges in the paper due to static electricity, thereby affecting its measurement.
Step-by-step explanation:
Electrons build up in human body, and when your finger gets close enough to anything through which they can flow to earth, they jump through the air in a spark of electric discharge. This creates static electricity as a result of flow of electron from your hand to conductive paper.
This changes the magnetic field and line of force of the point charges in the paper, thereby affecting its measurement.