Question

A glass marble is rubbed against a piece of silk. As a resultthe piece of fabric acquires extra electrons. What happens to theglass marble? (Select all that apply)

The marble has lost the same number ofelectrons acquired by the piece of silk.

The marble acquires a positive charge andrepels the piece of silk.

The marble acquires a negative charge andattracts the piece of silk.

The marble has acquired the same numberof electrons acquired by the piece of silk.

The marble acquires a positive charge andattracts the piece of silk.

The marble acquires a negative charge andrepels the piece of silk.

Answer 1

Concepts and reason

The concepts required to solve the given question is electrostatic force.

Initially, for the number of electrons by the piece of silk, apply the law of conservation of charge and for the nature of force between the marble and silk use the concept of Coulomb’s force.

Fundamentals

In an isolated system, the total charge remains conserved, that is, when a glass rod is rubbed against a piece of silk, the marble loose electrons and then becomes more electron deficient, which leads to acquiring of the positive charges on the glass marble and the piece of silk acquires extra electrons and becomes negatively charged.

According to the Coulomb’s law, the charges having same sign repel each other and the charges having different signs always attract each other.

When the glass marble is rubbed with a piece of silk, some electrons from the marble gets transferred to the piece of silk and hence, the marble acquires a positive charge and the silk acquires a negative charge.

Thus, the marble does not acquire a positive charge and does not repel the piece of silk, the marble doesn’t acquire a negative charge and does not attract the piece of silk, the marble doesn’t acquire a negative charge and doesn’t repel the piece of silk, and the marble has acquired the same number of electrons acquired by the piece of silk.

It is given that the piece silk fabric acquires extra electrons, when a glass marble is rubbed against it. Due to rubbing action of marble on the silk piece, the marble loses few electrons which are acquired by the piece silk fabric.

The number of electrons lost by the marble must the same as that of the number of electrons gained by the silk piece.

This is in accordance with the law of conservation of charges. Thus, the marble has lost the same number of electrons acquired by the piece of silk.

Since marble has lost electrons, it gains the positive charge and silk piece gains equal and opposite negative charge due to addition of electrons. The positive and negative charge exerts attractive force on each other.

This is in accordance with the Coulomb’s law, thus the marble acquires a positive charge and attracts the piece of silk.

Ans:

The marble has lost the same number of electrons acquired by the piece of silk.