Two 2.4 cm diameter disks spaced 1.5 mm apart form a parallel-plate capacitor. The electric field between the disks is 4.3×10^5 V/m.

What is the voltage across the capacitor?
How much charge is on each disk?
An electron is launched from the negative plate. It strikes the positive plate at a speed of 2.3×10^7 m/s. What was the electron's speed as it left the negative plate?

1 answer

E x d is the voltage
d is the plate separation

Use Gauss' Law or Q = CV for the charge

The change in kinetic energy equals e V