Explanation
- A plastic scale after being rubbed against dry hair attracts bits of paper as it acquires a negative charge due to its high work function than hair.
- It gets electrically charged due to rubbing.
- The bits of paper are electrically neutral.
- when charged plastic scale brought near to the bits of paper , geography of charges with in the paper changes ‘+’ comes upward and ‘-‘ go downward .
- plastic scale is negatively charged as it gained electrons . It exert electric force against the paper bits and attracts them.
But it does not happen in case of iron/metal scale . As metal is good conductor of electricity it allows charges to flow through them when we hold it in our hand all charges would come on our hand , it would be grounded .
No charges will Remain on the scale to exert electric force on the bits of paper.
