# Controls

Electric Field linearly accelerates $e^{-}$ from voltage in Electron Gun: Va
Magnetic Field circularly accelerates $e^{-}$ from current in Helmholtz coils through coils: Iα

## Task:Use the experiment to measure the ratio of the electrons charge to it's mass.

Fill the table with different acceleration voltages Va respectively coil currents I and the radius you will see in the experiment. So you can determine the charge to mass ratio.
$V_{\text a}~ \text {in V}$ $\Rightarrow v_0~ \text {in}\frac{\text m}{\text s}$ coil current
$I~\text {in A}$
$\Rightarrow B \text{ in T}$ Radius r
in cm
$\frac{e}{m}=\frac{2\cdot V_{\rm{a}}}{(B\cdot r)^2}~\text{in}\frac{\text C}{\text {kg}}$
$0$ $0$ $-$
$0$ $0$ $-$
$0$ $0$ $-$
$0$ $0$ $-$
$0$ $0$ $-$