In a cathode-ray tube (CRT), an electron travels in a vacuum and enters a region between two "deflection" plates which have equal and opposite charges. The dimensions of each plate are L = 13 cm by d = 4 cm, and the gap between them is h = 2.5 mm.
During a 0.001 s interval while it is between the plates, the change of the momentum of the electron is < 0, 5.60e-17, 0 > kg m/s.
What is the electric field between the plates?
What is the charge (both magnitude and sign) of the upper plate?
E is pointing upwards towards the upper plate from the bottom one.
Impulse = Force * Time
E= (Q/A)/(permittivity constant) "per"
The Attempt at a Solution
F = <0,5.6e-17,0>(kg*m/s) / .001(s)
Enet = F/Q
Enet = (Q/A)/"per"
Q=sqrt(8.854e-12(C^2/Nm^2) * <0,5.6e-14,0>(N) * .0052(m^2)
Well this is my attempt to find the charge and it seems I am doing something wrong, can you please point me in the right direction.