Solving for distance between plates, diameter of a capacitor

In summary, the task was to design a 5.02 pF air-filled capacitor with circular parallel plates that can withstand potentials of up to 95 V and has an electric field between the plates no greater than 1.40×104 N/C. Using the equations C=kEA/d, E=V/d, and A=pir^2, the distance between plates was found by using E=V/d and then plugging it into the capacitance equation to find the area of the plates. The radius of the circle was then found and multiplied by 2 to get the diameter. However, the system may have specific requirements for units and significant figures that should be carefully followed.
  • #1
PhysicsMan999
32
0

Homework Statement



  1. A 5.02 pF air-filled capacitor with circular parallel plates is to be used in a circuit where it will be subjected to potentials of up to 95 V. The electric field between the plates is to be no greater than 1.40×104 N/C. As an electrical engineer for Live-Wire Electronics, your task is to design the capacitor. What is its size? Enter the diameter and the separation of the plates.

Homework Equations


C=kEA/d
E=V/d
A=pir^2

The Attempt at a Solution


I used E=V/d to try and find the distance, then plugged that into the capacitance equation to find the area of the plates, which I then used to find the radius of the circle, which I multiplied by 2 to get the diameter.
 
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  • #2
PhysicsMan999 said:

Homework Statement



  1. A 5.02 pF air-filled capacitor with circular parallel plates is to be used in a circuit where it will be subjected to potentials of up to 95 V. The electric field between the plates is to be no greater than 1.40×104 N/C. As an electrical engineer for Live-Wire Electronics, your task is to design the capacitor. What is its size? Enter the diameter and the separation of the plates.

Homework Equations


C=kEA/d
E=V/d
A=pir^2

The Attempt at a Solution


I used E=V/d to try and find the distance, then plugged that into the capacitance equation to find the area of the plates, which I then used to find the radius of the circle, which I multiplied by 2 to get the diameter.
Just what I would have done! Congrats!
 
  • #3
CAPA says my answers are wrong though! The answers I'm getting are 0.00679 for the distance between plates, and around 0.07 for the diameter..
 
  • #4
PhysicsMan999 said:
CAPA says my answers are wrong though! The answers I'm getting are 0.00679 for the distance between plates, and around 0.07 for the diameter..
Did the system specify particular units to use? Is it finicky about significant figures?
 
  • #5
Well, apparently I was entering them in the wrong order..even though it says nothing about the order to enter them in. Thanks!
 
  • #6
PhysicsMan999 said:
CAPA says my answers are wrong though! The answers I'm getting are 0.00679 for the distance between plates, and around 0.07 for the diameter..
Well, I didn't check your math. I only endorsed your methodology! :smile:
 

Related to Solving for distance between plates, diameter of a capacitor

1. What is the equation for calculating the distance between plates of a capacitor?

The equation for calculating the distance between plates of a capacitor is d = ε*A/C, where d is the distance, ε is the permittivity of the material between the plates, A is the area of the plates, and C is the capacitance of the capacitor.

2. How does the distance between plates affect the capacitance of a capacitor?

The distance between plates has an inverse relationship with the capacitance of a capacitor. As the distance increases, the capacitance decreases. This is because the electric field becomes weaker with increasing distance, resulting in a decrease in stored charge and therefore, a decrease in capacitance.

3. Can the distance between plates be adjusted to change the capacitance of a capacitor?

Yes, the distance between plates can be adjusted to change the capacitance of a capacitor. This is commonly done by using a variable capacitor, where the distance between plates can be changed by rotating a knob or dial.

4. How does the diameter of a capacitor affect its capacitance?

The diameter of a capacitor does not directly affect its capacitance. However, it can indirectly affect the capacitance by affecting the area of the plates. The larger the area of the plates, the higher the capacitance will be.

5. Is there a limit to how close the plates of a capacitor can be?

Yes, there is a limit to how close the plates of a capacitor can be. This is because at very small distances, there is a risk of the plates coming into direct contact, which would result in a short circuit. Additionally, at extremely small distances, the electric field can become too strong and cause breakdown of the dielectric material between the plates.

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