Peoples Physics Concepts

http://www.ck12.org Chapter 15. Electric Circuits: Capacitors

Capacitor Lab (PhET Simulation)

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1. You have two 42μF and one 39μF all wired in parallel. Draw the schematic and calculate the total capacitance
   of the system.


2. You have two 42μF and one 39μF all wired in series. Draw the schematic and calculate the total capacitance
   of the system.


3. Given a capacitor with 1 cm between the plates a field of 20,000 N/C is established between the plates.
   a. What is the voltage across the capacitor?

b. If the charge on the plates is 1μC, what is the capacitance of the capacitor?

c. If two identical capacitors of this capacitance are connected in series what it the total capacitance?

d. Consider the capacitor connected in the following circuit at pointBwith two switchesSandT, a 20Ω

resistor and a 120 V power source:

a. Calculate the current through and the voltage across the resistor ifSis open andTis closed

b. Repeat ifSis closed andTis open

Answers

1. 123μF


2. 
   
   
   
   0. 073 μF
   
   
   
   


3. a. 6V b. 0.3A c. 18V d. 3. 6 × 10 −^4 C e. 3. 2 × 10 −^3 J f. i) 80μF ii) 40μF iii) 120μF