Hi, I hope the following explanation could help you out definitely.

J.J Thomson believed that apart from the atom's nucleus, there was also a teeny weeny particle in the atom. By this idea, he proposed that the existence of these particles could be found out. He began an experiment where he bombarded, i.e., shot a foil of gold, so thin, that its thickness was maybe nearly impossible to measure, with alpha particles, which are particles which you should not know in detail about. Moving on, he observed that about 70% of the alpha particles went straight through the gold foil. The rest, came back .This showed that the alpha particles were rebounded by the electrons in the atom.

After this experiment, he said that, "It was as if a bullet was shot at a tissue paper, and it bounced back", since alpha particles are very rapid, when it comes to moving.

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thank u.. but can u pls explain it in easy words
because i dont know anything from this topic... i need it in easy words please!!!!!! because today i was absent 2 my school and i have test tomorrow can u pls pls help out fast....
  • Brainly User
J.J.Thomson was the scientist who discovered electrons. He called them as ‘corpuscles’ – as universal building blocks of atom. 

His experiments showed, 
1. Cathode rays were electrically charged and could be deflected electrically.
2. Magnetic deflection of cathode rays
3. To measure the mass to charged ratio of cathode rays. 
For all the experiment he conducted he used cathode ray tube. This cathode ray tube is a sealed glass tube under vacuum. One end of the tube is an electrical filament called as cathode and the other end is the fluorescent screen. 

1. Cathode rays were electrically charged and could be deflected electrically.When an electric current is passed through the filament, it starts to glow.  If the fluorescent screen and filament are connected with electrical source electrical fielddevelops between the screen and the filament and if the screen considered positive, electrons travel from cathode(filament) towards screen causing it to glow. 
    The reason for the glow was mystery. Every one thought some rays were emerging. Thomson explained the rays responsible for the glow were due to the negative charged particles emitted from cathode also because electric current passed through the circuit. 
   He found that rays would bend in the presence of an electric field as expected for a negatively charged particle. 

2. Magnetic deflection of cathode raysThomson arranged the cathode ray tube, placed magnet above the path of ray. He found that the rays bent and negative charge was bent the same as, electrically charged objects were deflected by magnets. 
     This showed the rays were not as the beam of light as light does not bend by electric or magnetic field. 

3. To measure the mass to charged ratio of cathode rays. 
    He tried to measure the mass to charged ratio of cathode rays. He measured how far the rays were deflected by magnetic field and found mass to charged ratio of cathode rays was thousand times lesser than hydrogen ion, saying the particles in the rays were light and highly charged. 
     These conclusions were true as electrons were light and highly charged but carried negative charge exactly opposite to hydrogen ion.