# Oppositely Charged Parallel Plates

• mattwild
In summary: For c. I get the answer 1.7363 x 10^-9 seconds. Does that make sense?Yes, that looks correct. It's important to note that this is the time it takes for the electron to travel from one plate to the other, not the total time it takes for it to accelerate and reach the positively-charged plate. For that, you would need to consider the acceleration and distance traveled. In summary, two oppositely-charged parallel plates with a distance of 0.03m between them require 2.4x10^-19 J of energy to move an electron from one plate to the other. The strength of the electric field between the two plates is 50 N/C and
mattwild

## Homework Statement

Two oppositely-charged parallel plates are separated by a distance of 0.03m.

a. What is the strength of the electric field between the two plates if it takes 2.4x10^-19 J of energy to move an electron from one plate to the other.
b. What is the acceleration of that electron as it moves toward the positively-charged plate?
c. If the electron starts at rest, how long does it take to go from one plate to the other?
d. A Proton is launched in between the plates, moving parallel to them. Sketch the path this proton will take.

## The Attempt at a Solution

I'm really lost and not sure even what formulas to use except electric field strength but I have joules and I don't know what to do with that.

You're given the energy required to move the electron form one plate to the other. Sounds like work to me...

What do you know about work?

Ahhh that was the missing key. THANKS!

For b. I get the answer 8.7278 x 10^12 m/s2 after doing F=qE, and the F=ma using the electron mass and found force. Does that make sense?

mattwild said:
For b. I get the answer 8.7278 x 10^12 m/s2 after doing F=qE, and the F=ma using the electron mass and found force. Does that make sense?

That's the right ballpark. The value looks a bit off, but that might be due to the constants you're using. Can you post more of the work to show how you arrived at that acceleration?

By the way, keep in mind that it's always better to keep more digits through intermediate calculations and to not round anything until you get to the end. That prevents rounding errors from creeping into significant figures.

gneill said:
That's the right ballpark. The value looks a bit off, but that might be due to the constants you're using. Can you post more of the work to show how you arrived at that acceleration?

By the way, keep in mind that it's always better to keep more digits through intermediate calculations and to not round anything until you get to the end. That prevents rounding errors from creeping into significant figures.

W = Fd so F= W/d

E =Fe/q so E=W/dq

E= 2.4x10^-19 J/(0.03m)(1.6x10^-19)

E= 50 N/C

F=qE

F=1.6x10^-19 x 50

F = 8 x 10 ^ -18

F = ma

a = F/m

a= 8x10^-18/9.11x10^-31

a= 8.7819x10^12 m/s^2

Much better

## 1. What are oppositely charged parallel plates?

Oppositely charged parallel plates are two flat surfaces with equal and opposite electric charges facing each other. They are typically made of conductive materials such as metal and are used in various scientific experiments and devices, such as capacitors.

## 2. How do oppositely charged parallel plates create an electric field?

The electric charges on the two plates create an electric field in the space between them. The field lines go from the positive plate to the negative plate, indicating the direction of the electric force. This electric field can be manipulated by changing the distance between the plates or the amount of charge on each plate.

## 3. What is the purpose of using oppositely charged parallel plates in a capacitor?

A capacitor is a device that stores electric energy. Oppositely charged parallel plates are used in capacitors because the electric field between them allows for the storage of energy. The closer the plates are or the higher the charge on each plate, the more energy the capacitor can store.

## 4. How do oppositely charged parallel plates affect the movement of charged particles?

The electric field created by the oppositely charged parallel plates can exert a force on charged particles, causing them to move. The direction of the force depends on the direction of the electric field and the charge of the particle. This is the principle behind devices such as particle accelerators.

## 5. Can oppositely charged parallel plates ever have the same charge?

No, oppositely charged parallel plates must have equal and opposite charges. If they have the same charge, they will repel each other and will not have the necessary electric field to function as intended. This is why it is important to ensure that the plates are properly charged in experiments and devices involving oppositely charged parallel plates.

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