Could an orange or a lemon, which also contain seeds inside soft pulp, be a good comparison? In what ways does it match Thomson’s idea and where does it fall short?
An orange or a lemon can partially match Thomson’s idea. The soft pulp of the fruit represents the sphere of positive charge, while the seeds inside represent the negatively charged electrons.
However, the comparison falls short because in an orange or lemon, the seeds are not distributed throughout the entire pulp; they are localized in specific segments or the center. According to Thomson’s model, the electrons must be distributed throughout the entire sphere of positive charge, similar to how watermelon seeds are spread uniformly across its red pulp.
Explanation
The textbook uses a watermelon as a comparison for Thomson's model because its seeds are distributed throughout the pulp, accurately reflecting Thomson's idea of electrons spread throughout a sphere of positive charge. An orange or lemon falls short as an analogy because its seeds are not spread uniformly throughout the pulp, which misrepresents the uniform distribution of electrons required by the model.