Wie rechne ich.. die Elektronenablenkung in einer Braun'schen Röhre?

Gegeben:

clear all;
x = 0.01; %1cm
v_x = 9e6; %m/s
E_y = 1000; %N/C;
q = 1.602e-19; %C
m_e = 9.11e-31; %kg
g = 9.81; %m/s
d = 0.2; %20cm

Zeit

t = x ./ v_x
t = 1.1111e-09

Spielt die Gravitationskraft eine Rolle?

F_el = q * E_y;
F_G = m_e * g;
verhaeltnis = F_el / F_G
verhaeltnis = 1.7926e+13

Ablenkung

%F == F_el
a = q*E_y / m_e
a = 1.7585e+14
y_1 = 0.5*a*t^2
y_1 = 1.0855e-04
v_y = a * t
v_y = 1.9539e+05
alpha = atand(v_y / v_x)
alpha = 1.2437

Schirm

y_2 = d*tand(alpha)
y_2 = 0.0043
y = y_1 + y_2
y = 0.0045