1. Capacitors ( )
Capacitors are elements used in circuits to store electric charge (and energy) and to block surges of electricity, protecting circuits

2. Capacitors: what are they?
Caps typically consists of 2 conducting plates placed near each other but not touching.
Sometimes they are wrapped into a cylinder like a burrito or one of those “healthy wraps”
Capacitors: what are they?

3. Capacitor is basically 2 places separated by an air gap (the gap can be filled with a dielectric to increase the capacitance)
Capacitor

4. They look like this
Capacitor

5. Circuit with capacitor, resistor, battery
Caps in circuits

6. When placed in a circuit and voltage source, charges flow onto the plates.
Q = CV = total charge on the capacitor
C is called the Capacitance and its measured in Farads.
C depends on the geometry of the Capacitor…C = ЄA/d where Є = a constant , A is the area of the plate, and d = distance between the plates.
Capacitors

7. Capacitors and Dielectrics
A dielectric is a material which is placed between the plates in a capacitor.
A dielectric does not allow electric charge to jump across the gap as easily as air, so higher voltages can be used.
Dielectrics also increase the Capacitance of the capacitor.
Capacitors and Dielectrics

8. Dielectrics increase the capacitance by a factor of K.
K = dielectric constant = material property
C = KЄA/d
Mtl K
Vacuum 1.0
Paper 3.7
Rubber 6.7
Waffle 9.3
Dielectrics (17.8)

9. Energy in a capacitor Caps store energy
E = ½ CV2 (V = Voltage, not velocity…duh)
Energy in a capacitor

10. Capacitors in circuits (19.5) Caps in parallel have the same Voltage
Caps in Parallel have the same voltage and you find the total charge Q on each plate using Q = CV.
Capacitors in circuits (19.5) Caps in parallel have the same Voltage

11. Capacitors in Series: Each plate of the caps in series has the same CHARGE = Q

12. Capacitors in series and parallel
The rules for “combining capacitors” in a circuit is just the opposite as the resistor rules…..
Circuit Voltage Charge Cequiv
Parallel Same Adds Ceq=C1+C2
Series Adds Same I/Ceq= 1/C1 + 1/C2
Capacitors in series and parallel