Write observations of various experiments which suggest that cathode rays are a stream of negatively charged particles.

(A) In $1870$,William Crookes performed experiments with a gas discharge tube.
He filled a gas in the discharge tube at low pressure and applied a high electric field to the electrodes at both ends of the tube.
He observed that electric rays (cathode rays) were produced,which traveled from the cathode to the anode. When these rays struck a fluorescent material,they produced a yellowish glow.
$J$.$J$. Thomson further investigated these rays and observed that they could be deflected by electric and magnetic fields,confirming they carry a negative charge.
$J$.$J$. Thomson measured the speed of cathode rays,finding it to be in the range of $\frac{1}{20}$ to $\frac{1}{30}$ times the speed of light $(3 \times 10^{8} \ m/s)$.
He determined the specific charge (ratio of charge to mass,$\frac{e}{m}$) of these particles to be approximately $1.76 \times 10^{11} \ C/kg$.
He concluded that the specific charge $\frac{e}{m}$ is independent of the type of gas used in the tube and the material of the electrodes,suggesting that these particles (electrons) are universal constituents of all matter.