Related: Why two objects get charged by rubbing?
After reading the above question’s answer given by Luboš Motl in terms of the triboelectric effect, I believe I have a good grasp on how charge is transferred between two different materials.
My question is why does plastic wrap, made of one type of material, when pulled from a roll gets one side negatively charged while the other side gets positively charged?
I was unable to understand this question after reading several links on the triboelectric effect and electronegativity. It appears to me that this effect is responsible for two different materials transferring charge but was unclear to me when speaking on how charge is transferred between the same material, as in the case of the plastic wrap. I’d appreciate any help for a correct explanation.
Best Answer
Because the surface of the plastic wrap is much larger than its thickness, it behaves like a capacitor, accumulating positive charge on one side and negative charge on the other. It creates a potential difference and thus an electric field.