Q5 of 22 Page 113

Why did Thomson assume that electrons are embedded in a positively charged sphere? Why did he not assume that they are positively charged particles embedded in a negatively charged sphere?

Before putting forth his model, he concluded from the experiments that:

1. Atoms contain negatively charged particle called electrons.


2. Atom is neutral in nature.


So, to neutralize the negative effects of electrons, he explained his model as a large sphere where positive charge is continuously distributed and electrons are embedded in it.


More from this chapter

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5

Observe the size and direction of your shadow, when you stand in the sunlight in the morning and in the evening.


(i) Is the length of your shadow the same as your height?


(ii) What is the direction of the shadow? Does it fall in the direction of the source of light or in the direction opposite to the light source?


(iii) Compare the nature of the shadow formed in this activity with that of the shadow formed when an object is kept in the path of the cathode rays.

 5

(i) Sketch and label the parts A,B,C,D and E in the figure given below:


(ii) What is the purpose of B?


(iii) What is the function of D?

 5

Cathode and Anode rays are negatively and positively charged particles respectively. They travel in a direction opposite to each other. Why don't they get neutralized?

 1

Construct a model of Thomson’s atom using a cardboard, chart paper cut in round shape, gum, cotton, red colour sketch pen /water colour and dry black watermelon seeds or black beads. Label the model and display it in your classroom. Write a brief description of the Thomson’s model.