The Greek philosopher Democritus $(460BC),$ the English chemist Dalton $(1844$ AD$),$ and Russian chemist Mendeleyev $(1834)$ contributed to the development of the atomic

theory. But their idea was wrong, because they thought an atom is an elemtary particle, that cannot be taken apart. J$.$ J$.$ Thomson $(1856)$ discovered that atoms have

internal structure. And he discovered the first truly elementary particle$--$the electron.

What experiments and what theories did Thomson study?

all particles in a cathode ray have the same value of $\frac{q}{m}$

cathode rays in an electric field to prove that an atom contains negative charge

experiments on cathode rays

an atom is like a tiny solar system

an atom contains both positive and negative particles

all particles in a cathode ray have the same value of $q$

TRUE or FALSE?