Determine the dielectric constant

AI Thread Summary
To determine the dielectric constant for the parallel plate capacitor, the surface charge density and potential difference are used. The area of the plates is calculated using the formula A = πr^2, where r is the radius. The capacitance can be expressed as C = K*(ε0)*(A/d), where ε0 is the permittivity of free space. The charge can be calculated by multiplying the surface charge density by the area. The dielectric constant K can then be derived from the relationship between charge, capacitance, and potential difference.
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Homework Statement


Two flat metal circles of radius r=15 mm are brought a distance d=8.0 mm apart to form a parallel plate capacitor. The surface charge density of one plate is measured to be +1.0*10^-3 microCouloubs/mm^2. The potential difference across the capacitor is measured to be .12 Volts. There is a dielectric between the plates. What is the dielectric constant.


Homework Equations


C=K*(E0)*[A/d]
A=(pi)r^2
Q= CV... maybe


The Attempt at a Solution


I plugged what I had into the equation, but I don't know how to find the capacitance using the surface charge density.
I have
C= K(8.85*10^-12)*[pi*(.015^2)/.008]
 
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Find the area of the plate(mm2), then multiply that by the density to give charge.
 

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