Capacitors come in all shapes and sizes….
Similar principle can be used for “touch screens” of
tablets, smart phones, etc.
Parallel plate capacitor
Note: it is ASSUMED that charge is equal and opposite on the two plates
Electric field is APPROXIMATELY perpendicular to the plates everywhere
between the plates.
Why are there “fringing” fields (ie. not straight) near the edges of the
capactior?
Clicker Question #1
What is the equivalent capacitance of the network below?
A)
B)
C)
D)
E)
0.625 μF
1.6 μF
42 μF
18 μF
Impossible to tell. Capacitors not in
series or parallel
E
Clicker Question #2
What is the equivalent capacitance of the network below?
A)
B)
C)
D)
E)
0.625 μF
1.6 μF
42 μF
18 μF
Impossible to tell. Capacitors not in
series or parallel
E
Clicker Question #3
What is the equivalent capacitance of the four capacitors?
A) 3.6μF
B) 3.3 μF
C) 15 μF
D) 0.33 μF
E) None of the above
B
A
C
Clicker Question #4
What is the equivalent capacitance between points a and b?
A) 0.5μF
B) 12.9 μF
C) 0.077 μF
D) 2 μF
E) None of the above
B
A
C
Clicker Question #5
What is the equivalent capacitance between points a and b?
A) 1.5μF
B) 3 μF
C) 1.3 μF
D) 2 μF
E) None of the above
B
A
C
Microscopic view of Dielectrics
Clicker Question #6
Capacitor C1 is initially charged to voltage Vo using the battery as shown in the figure.
The capacitor C1 is then disconnected from the battery and then connected to an
UNCHARGED capacitor C2. Which of the following statements is FALSE?
A) When the capacitors are connected, charge will flow from capacitor C1 to C2.
B) The final voltages on capacitors C1 and C2 are equal.
C) The final charges on capacitors C1 and C2 are equal.
D) Two of the above statements are False.
B
E) A, B, and C are true
A
C