(ii) What evidence is there that electrons are
negatively charged
particles?
Answers
Answer:
J.J. Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons. Thomson's plum pudding model of the atom had negatively-charged electrons embedded within a positively-charged "soup."
Answer:
The entire concept that electrons are negatively charged is purely a matter of convention. If you take a proton to be positively charged then by nature of charges any charge that repels a proton must be taken positive and any charge that attracts it must be taken negative.
There are many ways in which you can prove that electrons have negative charge.
You can prove it theoretically by considering the model of an atom. Any two body system consisting of like charges will have greater potential energy than a system with opposite charges. If you calculate the energy of such systems, you will realise the only way the atom can be stable is when one the electron is opposite in charge to the proton. There are more theoretical ways in which you can prove this by using quantum mechanics which is a bit complicated but if you want to know more then I'd suggest you to do further reading on this.
As for practical experiments, you can perform JJ Thompson's famous cathode ray experiment, or read about it. That famous experiment necessarily proves that atoms are surrounded by particles which have negative charge. And I guess, if you perform experiments with static electricity then also you can arrive at the conclusion that electrons have negative charge
Explanation: