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 #1What is the equivalent capacitance of the network below?

E

A) 0.625 μFB) 1.6 μFC) 42 μFD) 18 μFE) Impossible to tell. Capacitors not in

series or parallel

Clicker Question #2What is the equivalent capacitance of the network below?

E

A) 0.625 μFB) 1.6 μFC) 42 μFD) 18 μFE) Impossible to tell. Capacitors not in

series or parallel

Clicker Question #3What is the equivalent capacitance of the four capacitors?A) 3.6μFB) 3.3 μFC) 15 μFD) 0.33 μFE) None of the above

A

B

C

Clicker Question #4What is the equivalent capacitance between points a and b?A) 0.5μFB) 12.9 μFC) 0.077 μFD) 2 μFE) None of the above

A

B

C

Clicker Question #5What is the equivalent capacitance between points a and b?A) 1.5μFB) 3 μFC) 1.3 μFD) 2 μFE) None of the above

A

B

C

Microscopic view of Dielectrics

Clicker Question #6Capacitor 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.E) A, B, and C are true

A

B

C