Cathode Rays: What are they?
Thomson’s experiments supported the charged particle theory of cathode rays. Why?
Measurements of the deflection of cathode rays by Electric and Magnetic Fields were consistent with what would be expected if the rays were actually charged particles with a definite ratio of electric charge to mass.
- Electric Force (Fe) = Electric Field (E) x charge of particle (q)
- Newton’s Second Law ? ae = Fe / m = E (q/m)
- Magnetic Force (Fm)= Magnetic Field (B) X charge (q) x velocity (v)
- Newton’s Second Law ? am = Fm / m = B v (q/m)
- By measuring both the electric & magnetic deflections allow determination of both the velocity (v) & charge-to-mass ratio (q/m)