Find Radius of Outer Sphere for 1uF Spherical Condenser

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In summary, the capacitance of a spherical condenser is 1uF and the radius of the outer sphere is 10^-3.
  • #1
James2911
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Homework Statement


The capacitance of a spherical condenser is 1uF. If the spacing between the two spheres is 1mm, then what is the radius of the outer sphere

Homework Equations


[/B]
C = 4 pi Epsilon * ab/b-a (for a spherical capacitor)

The Attempt at a Solution



Given C = 1uF (u = 10^-6)
b-a = 10^-3

1uF = 4 pi Epsilon * ab/10^-3
On solving
9 = ab

How do I proceed forward from here? Please help
 
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  • #2
James2911 said:

Homework Statement


The capacitance of a spherical condenser is 1uF. If the spacing between the two spheres is 1mm, then what is the radius of the outer sphere

Homework Equations


[/B]
C = 4 pi Epsilon * ab/b-a (for a spherical capacitor)

The Attempt at a Solution



Given C = 1uF (u = 10^-6)
b-a = 10^-3

1uF = 4 pi Epsilon * ab/10^-3
On solving
9 = ab

How do I proceed forward from here? Please help
You have two equations and two unknowns.
Apply the standard method of solving simultaneous equations. Use one equation to express one variable in terms of the other, then substiute for it in the other equation.
 
  • #3
haruspex said:
You have two equations and two unknowns.
Apply the standard method of solving simultaneous equations. Use one equation to express one variable in terms of the other, then substitute for it in the other equation.
Yes I did but this is what happened;
ab = 9 -------- (1)
b-a = 10^-3
b = a + 10^-3 -- substituting in (1)

a(a+10^-3) = 9
Still stuck! :(
 
  • #4
James2911 said:
Yes I did
Next time, please post your working as far as you get in the first post.
James2911 said:
a(a+10^-3) = 9
Still stuck! :(
It's just a quadratic equation. But it should be obvious what a will be approximately.
By the way, I did not check your derivation of ab=9.
 
  • #5
haruspex said:
Next time, please post your working as far as you get in the first post.

It's just a quadratic equation. But it should be obvious what a will be approximately.
By the way, I did not check your derivation of ab=9.
I never saw that quadratic equation coming! Thank you. This it!
 

Related to Find Radius of Outer Sphere for 1uF Spherical Condenser

1. What is a 1uF spherical condenser?

A 1uF spherical condenser is a type of capacitor that has a capacitance of 1 microfarad (uF). It consists of two conductive spherical plates separated by a dielectric material, such as air or a non-conductive material. When a voltage is applied to the plates, it stores electrical energy.

2. Why is it important to find the radius of the outer sphere for a 1uF spherical condenser?

Finding the radius of the outer sphere is important because it determines the overall size and capacitance of the spherical condenser. It also affects the electric field strength and the amount of energy that can be stored in the condenser.

3. How is the radius of the outer sphere calculated for a 1uF spherical condenser?

The radius of the outer sphere can be calculated using the formula r = √(C/4πε), where r is the radius in meters, C is the capacitance in farads, and ε is the permittivity of the dielectric material in farads per meter (F/m).

4. What is the permittivity value for air as the dielectric material in a 1uF spherical condenser?

The permittivity value for air is approximately 8.854 x 10^-12 F/m. This value may vary slightly depending on factors such as temperature and pressure.

5. Can the radius of the outer sphere be changed for a 1uF spherical condenser?

Yes, the radius of the outer sphere can be changed by altering the distance between the two conductive plates. However, the capacitance will also change accordingly, as it is directly proportional to the radius. The permittivity and the type of dielectric material used can also affect the radius of the outer sphere.

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