Chapter 4, Problem 49A

Interpretation Introduction

Interpretation:

Experimental results that led to the conclusion that electrons are a part of all forms of matter is to be determined.

Concept introduction:

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

Answer to Problem 49A

There was no change in the ray produced even though the type of gas or type of electrodes was changed.

Explanation of Solution

Experiments which show electrons are negatively charged are as follows:

Cathode-ray tube: In this experiments, the ray that are stream of particles, had originated from the cathode and traveled to the anode as they have negative charge. The bend towards positively charged plates shows that electrons are negatively charged.

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

It was found out that when the type of electrodes or the type of gas was changed, there was no change in the ray produced. Eventually, the researchers led to the conclusion the electrons are a part of all the forms of matter.

Conclusion

Thus, the fact that changing the type of electrode or the type of gas used in the cathode ray tube didn’t have any effect on the ray produced concluded that the electrons are present in all matter.