In mass spectrometer used for measuring the masses of ions, the ions are initaily accerlerated by an electric potential `V` and then made to describe semicircular paths of radius `R` using a magnetic field `B`.if `V` and `B` are kept constant, the ratio `(("charg e on the ion")/("mass of the ion"))` will be propertional to:

Options

A. `R`
B. `1/R`
C. `(1)/(R^2)`
D. `R^2`

Answer

C

Explanation

`r = (mv)/(qB) = (sqrt(2mE) )/(qB) = (sqrt(2mqV) )/(qB)`
` r^2 = (2mV)/(qB^2) rArr q/m = (V^2)/(r^2 B^2) rArr q/m prop (1)/(r^2)`