Chapter 16, Problem 5Q

To determine

To reason behind the picking of a piece of a paper by a plastic ruler when it is rubbed with a cloth and difficult to pick up during the humid day.

Explanation of Solution

Introduction

Static electricity is defined as the charge acquired by an object when the positive and negative ions are imbalance.

When a plastic ruler is rubbed on a cloth, it gains some electron from the cloth. When it came brought to piece of paper, it draws positive charges due to polarization and repels the negative charges due to which a net attractive charge is generated. This net attractive charge create an electrostatic force that attracts the piece of paper.

During the humid day, the water molecules are available in the air and these have polar nature. Due to its polar nature, the water molecules attracts a fraction of charge from the ruler and the ruler becomes less polarized that’s why a plastic ruler not able to pick up the piece of paper during humid day.

Conclusion:

Therefore, the plastic ruler is able to pick up piece of paper due to electrostatic force and it is not able to pick up piece of paper during the humid day due to the annihilation by the water molecules.