Determination of Specific Charge

Question 1

Derivation of Equation

Answer 1

evB = mv^2/r

v = eBr/m

eV = 0.5mv^2

eV = 0.5 m (eBr/m)^2

e/m = 2V/B^2 r^2

v = velocity
V = Voltage
m = mass of electron

Question 2

Significance of Thompsons determination

Answer 2

Magnitude of e/m of electron was much greater than that of a hydrogen ion. With similar charges, the cathode ray particles would have to be a lot smaller than a hydrogen ion (smaller than an atom).