In an experiment for positive ray analysis with Thomson method, two identical parabola are obtianed when applied electric fields are `3000` and `2000 V//m`. The particles are singly ionised particles assuming same magnetic field :

Options

A. `1 : 3`
B. `2 : 4`
C. `3 : 1`
D. `4 : 2`

Answer

A

Explanation

For same magnetic field `(y^(2))/(x) prop (1)/(E) ((e)/(m))`
For singly ionised particle, `(y^(2))/(x) prop (1)/(E_(1)) (e)/(m_(1))`
Fro doubly ionised particle, `(y^(2))/(x) prop (1)/(E_(2)) (2e)/(m_(2))`
Since the parabolas for both the particles are identical,
`(1)/(E_(1)) (e)/(m_(1)) = (1)/(E_(2)) (2e)/(m_(2))`
So `(m_(1))/(m_(2)) = (E_(2))/(2E_(1)) = (2000)/(2 xx 3000) = (1)/(3)`