Physics 2

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Practice Problems: Capacitors

1. (easy) Determine the amount of charge stored on either plate of a capacitor (4x10-6 F) when connected across a 12 volt battery.

2. (easy) If the plate separation for a capacitor is 2.0x10-3 m, determine the area of the plates if the capacitance is exactly 1 F.

3. (moderate) Calculate the voltage of a battery connected to a parallel plate capacitor with a plate area of 2.0 cm2 and a plate separation of 2 mm if the charge stored on the plates is 4.0pC.

4. (easy) A parallel plate capacitor is constructed of metal plates, each with an area of 0.2 m2. The capacitance is 7.9nF. Determine the plate separation distance.

5. (easy) A capacitor (parallel plate) is charged with a battery of constant voltage. Once the capacitor reaches maximum charge, the battery is removed from the circuit. Describe any changes that may take place in the quantities listed here if the plates were pushed closer together.
a. Charge
b. Capacitance
c. Voltage
d. E-field

6. (moderate) Random access memory chips are used in computers to store binary information in the form of "ones" and "zeros". One common way to store a "one" is to charge a very small capacitor. Of course, the same capacitor without charge represents a "zero". A memory chip contains millions of such capacitors, each coupled with a transistor (that acts as a switch), to form a "memory cell". A typical capacitor in a memory cell may have a capacitance of 3x10-14 F. If the voltage across the capacitor reading a "one" is 0.5 v, determine the number of electrons that must move on the the capacitor to charge it.

7. (easy) C1 = 10 F and C2 = 5 F. Determine the effective capacitance for C1 and C2 connected in series and in parallel.

8. (moderate) If the two capacitors in question #7 were connected to a 50 volt battery determine the voltage across the capacitors for each connection type.

9. (moderate) Evaluate the circuit shown below to determine the effective capacitance and then the charge and voltage across each capacitor . 10. (moderate) Evaluate the circuit shown below to determine the effective capacitance and then the charge and voltage across each capacitor. 11. (moderate) Evaluate the circuit shown below to determine the effective capacitance and then the charge and voltage across each capacitor. 