Question

give an example to show that cathode rays 1) travel in a straight line 2) consist of material particles​

Answer 1

1. Unless disturbed by any magnetic or electric field, cathode rays (electrons essentially) keep travelling in a straght line untill they hit the anode on the opposite side of the vacuum tube, because they tend to traverse the shortest distance from cathode to anode, which of course is a straight line.

2.Thomson showed that cathode rays were composed of a previously unknown negatively charged particle, which was later named the electron. Cathode ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to render an image on a screen.