Dielectric Constant

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1. Feb 24, 2016

JordanHood

1. The problem statement, all variables and given/known data
A parallel plate capacitor has a capacitance of 1.5µF with air between the plates. The capacitor is connected a 12V battery and charged. The battery is then removed. When a dielectric is placed between the plates, a potential difference of 5.0V is measured across the plates. What is the dielectric constant of the material?

2. Relevant equations

3. The attempt at a solution
I know that Q=CV. however this is the only equation I find relevant as all the other equations I know for finding the dielectric constant involve area and distance between the plates. Can someone just help me get started with this question?

2. Feb 24, 2016

cnh1995

Inserting a dielectric will increase the capacitance but charge on the the plates will be same. Can you write an equation with this information and find the new capacitance? Comparing the two capacitances, you can calculate the dielectric constant of the new capacitor.