- #1

Squall

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## Homework Statement

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.

## Homework Equations

Impulse = Force * Time

F= q*Enet

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"

F/Q=(Q/A)/"per"

Q=sqrt("per"*F*A)

Q=sqrt(8.854e-12(C^2/Nm^2) * <0,5.6e-14,0>(N) * .0052(m^2)

Q=5.077e-14C

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.

Thank You