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**Please, can someone help me quickly with these two problems!!!!!**

**1. Homework Statement**

A parallel plate capacitor is constructed with a dielectric constant ( k = 3 * 10^8) The maximum projected voltage is 5000v and the capacitance needed is .5 micro Farads. Calculate the plate area.

**2. Homework Equations**

Q =VC, C = AE/d, C = KC

**3. The Attempt at a Solution**

Well, I can solve for Q, but that doesn't help. Also I don't know d!. Is 5 microfarads before or after the influence of the dielectric?

Another one, please :)

**1. Homework Statement**

Compute the capacitance on a cylindrical capacitor of length 5cm. This capacitor consists of two hollow concentric cylinders with radii of 1.5mm and 4mm (surface area of cylinder is 2pirl)

**2. Homework Equations**

2pirl, Q=VC

**3. The Attempt at a Solution**

I don't know the cylinder equations!