Phys 222 SI Worksheet #9
Capacitors
1. If a square capacitor has side 6cm and the distance between the plates is 0.15mm, what is
the charge on the capacitor when the voltage across it is 15V? What is the internal energy of
this capacitor?
2. What is the total capacitance between the two points in the following pictures?
3. A spherical capacitor with length 15m stores 3.2*10-9J of energy when the potential
difference across it is 4V. a) Calculate the magnitude of the charge on each conductor. b)
calculate the ratio of the radii of the inner and outer conductors.
4. A spherical capacitor with inner radius 4mm and outer radius 5mm is connected in series
with a cylindrical capacitor with the same inner and outer radii and length 85cm. What is the
energy stored when the total voltage across the capacitors is 13V?
5. A 12.5µF capacitor is connected to a power supply that keeps a constant potential difference
of 24V across the plates. A piece of material with dielectric constant 2.75 is placed between the
plates. How much energy is stored before and after the dielectric is inserted?
6. What is the total capacitance of the circuit below?