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Announcements Homework for tomorrow…
Ch. 29: Probs. 20, 22, & 54CQ5: accelerates rightCQ6: a) Va>Vb b) ΔVab<ΔVcd<ΔVef c) yes, no29.8: 1.5 V29.12: Ex(0cm<x<2cm) = +2,500 V/m Ex(2cm<x<3cm) = -10,000 V/m29.15: a) 27 V/m b) 3.7 V/m
Office hours…MW 12:30-1:30 pm TR 9-10 am F 1-2 pm
Tutorial Learning Center (TLC) hours:MW 8-10 am, 12-6 pm R 8-12 pm, 2-6 pm T 8-1 pm, 2-6 pm F 8-10 am, 2-5 pm
Chapter 29
Potential & Field(Combinations of Capacitors)
Kirchoff’s Loop Rule…
Conductors in Electrostatic Equilibrium…
Capacitance…
Review…
Any two electrodes, regardless of their shape, form a capacitor.
The capacitance of two electrodes is..
and depends only on the geometry of the electrodes.
Forming a Capacitor…
The spacing between the plates of a 1.0 μF capacitor is 0.050 mm
a. What is the surface area of the plates?
b. How much charge is on the plates if this capacitor is attached to a 1.5 V battery?
i.e. 29.6: Charging a capacitor
Consider two capacitors in parallel… Can we find an equivalent capacitor, Ceq, to the two
capacitors, C1 & C2?
Combinations of Capacitors
+
-
C1 C2
+
-
Ceq
Consider two capacitors in parallel… Can we find an equivalent capacitor, Ceq, to the two
capacitors, C1 & C2?
YES!
Combinations of Capacitors
+
-
C1 C2
+
-
Ceq
What about for several capacitors in parallel? Can we find an equivalent capacitor, Ceq, to the
capacitors, C1 , C2, … (all in parallel)?
Combinations of Capacitors
+
-
C1 C2
+
-
CeqC3
What about for several capacitors in parallel? Can we find an equivalent capacitor, Ceq, to the
capacitors, C1 , C2, … (all in parallel)?
YES!
Combinations of Capacitors
+
-
C1 C2
+
-
CeqC3
Consider two capacitors in series… Can we find an equivalent capacitor, Ceq, to the two
capacitors, C1 & C2?
Combinations of Capacitors
+
-
C1
C2
+
-
Ceq
Consider two capacitors in series… Can we find an equivalent capacitor, Ceq, to the two
capacitors, C1 & C2?
YES!
Combinations of Capacitors
+
-
C1
C2
+
-
Ceq
What about several capacitors in series? Can we find an equivalent capacitor, Ceq, to the
capacitors, C1 , C2 ,… (all in series)?
Combinations of Capacitors
+
-
C1
C2
+
-
Ceq
C3
What about several capacitors in series? Can we find an equivalent capacitor, Ceq, to the
capacitors, C1 , C2 ,… (all in series)?
YES!
Combinations of Capacitors
+
-
C1
C2
+
-
Ceq
C3
The equivalent capacitance is
1. 9 F.
2. 6 F.
3. 3 F.
4. 2 F.
5. 1/2 F.
Quiz Question 1
Find the charge on and the potential difference across each of the three capacitors in the figure below.
Given: E = 12 V, C1 = 3 μF, C2 = 5 μF , C3 = 1 μF
i.e. 29.7:A Capacitor Circuit
+
-
C1
C2 C3