Nov. 4, 2019

Cathode Rays and Positive Rays:

Cathode Rays

They are streams of fast moving electrons.

J.J. Thomson’s Experiment

eV = 1/2 mv2 = e/m = v2/2V ⇒ = e2/2VB2

em = 1.77×1011 C/kg.


Millikan’s Oil Drop Experiment

Milikan performed the pioneering oil drop experiment for the precise measurement of the charge on the electron. 

In this experiment charge on the drop is given by

q = 6πη(V1v2)d/v [V1/2g(ρ- σ)]1/2

Positive Rays or Canal Rays

(q/m)v or positive rays is much smaller than that of cathode rays and is not a universal constant.