Question

importance of shadow-
id like to understand about shadow, why they say something has to travel in order to form a shadow ?

Answer 1

my notes has :

In one of his experimental investigations, Crookes placed an object within the path of the cathode ray. Because a \(shadow\) appeared on the positive electrode, Crookes concluded that something (either light or small particles) was traveling from the negative to the positive electrode. Crookes hypothesized that the glow was made up of small particles of matter, but the scientific community would need more evidence before they would accept this idea.