Chapter 4.2, Problem 9SSC

Interpretation Introduction

Interpretation: The experiments leading to the conclusion that electrons are negatively charged particles found in all matter needs to be explained.

Concept introduction: An atom is the smallest particle in the element that can neither be created nor be destroyed. Various physicists have given various models of an atom to describe its structure and properties such as Dalton’s atomic model, J.J. Thomson’s model, Rutherford’s model and Bohr’s model.

Explanation of Solution

The experiments leading to the conclusion that electrons are negatively charged particles found in all matter are:

Cathode-ray tube: In this experiment, the ray that is a stream of particles originated from the cathode and traveled to the anode which is negatively charged. The bend towards positively charged plates confirms the negatively charged nature of electrons.

Oil drop experiment: Robert Millikan uses the oil-drop apparatus to confirm the negative charge of an electron as -1 and calculated its mass as $9.1\times {10}^{-28}\text{g}$ .