acceleration voltage Va

$v_0= \sqrt{2\cdot \frac{e}{m}\cdot V_{\text a}} =$ ${2.652\cdot 10^7}$ $\frac{\text m}{\text s}$

plate voltage Vp

$E=\frac {V_{\text p}}{\text d}=$ ${0}$ $\frac {\text V}{\text m}$

schematic diagram:

Schematic layout of the experiment
Real experiment about deflection of electrons in electric field of a plate capacitor
y(x) =

Replace in ${y(x)=\frac{V_\text p\cdot e}{2\cdot \text d\cdot m \cdot {v_0}^2}\cdot x^2}$ the initial speed ${v_0}$ of the electrons caused by the electron gun with a term that only depends on the acceleration voltage $V_{\text{a}}$, which can be modified in the experiment.

Useable variables:

x  = position on x-axis
Va = acceleration voltage
Vp = capacitor voltage
e  = charge of an electron
m  = mass of an electron
d  = distance between capcitor plates

typing tips:

x² must be typed as x*x
2x must be typed as 2*x