280 likes | 293 Views
Physics 123. 19. DC Circuits. 19.1 Resistors in Series and Parallel 19.6 Capacitors in Series and Parallel 19.7 RC Circuit 19.10 Ammeters and Voltmeters. L3. L1. L2. L4. Bulbs in Series and Parallel. A. L1 and L2 are in series B. L1 and L2 are in parallel
E N D
19.DC Circuits 19.1 Resistors in Series and Parallel 19.6 Capacitors in Series and Parallel 19.7 RC Circuit 19.10 Ammeters and Voltmeters
L3 L1 L2 L4 Bulbs in Series and Parallel A. L1 and L2 are in series B. L1 and L2 are in parallel C. L3 and L4 are in series D. None of the above
L3 L1 L2 L4 Bulbs in Series and Parallel L1 and L2 are in series and L3 and L4 are in parallel
L3 L1 L2 L4 Bulbs in Series and Parallel A. I1 = I2 B. V1 = V2 C. I3 = I4 D. None of the above
L3 L1 L2 L4 Bulbs in Series and Parallel Series Parallel I1 = I2 V3 = V4
L1 L2 Which bulb is brighter? A. L1 and L2 are equally bright B. L1 is brighter than L2 C. L2 is brighter than L1 D. None of the above
L1 L2 Which bulb is brighter? None of the above. Brightness depends on power (watts) which is P = VI or P = I2R. In general, L1 and L2 will shine differently unless they are the same type of bulb. Different bulbs have different values of filament resistance.
L3 L4 Brightness of Bulbs in Parallel A. L3 and L4 are equally bright B. L3 is brighter than L4 C. L4 is brighter than L3 D. None of the above
L3 L4 Brightness of Bulbs in Parallel None of the above. Brightness depends on power (watts) which is P = VI or P = V2 / R. In general, L1 and L2 will shine differently unless they are the same type of bulb. Different bulbs have different values of filament resistance. The bulb with the smaller resistance will be brighter in this case!
L1 L2 L1 L2 What’s wrong with this picture? In which circuit is L2 brighter? In which circuit is L1 brighter?
L1 L2 L1 L2 What’s wrong with this picture? In which circuit is L2 brighter? … Just kidding! In which circuit is L1 brighter? … Well, L1 will not light up without L2 in a series circuit.
L3 L4 Bulbs in Series and Parallel L3 In which circuit is L4 brighter? In which circuit is L3 brighter?
L3 L4 Bulbs in Series and Parallel L3 In which circuit is L4 brighter? … Just kidding! In which circuit is L3 brighter? L3 will be equally bright in both circuits … And I am DEAD SERIOUS. The voltage is the same, the current is the same , the power is the same, the brightness is the same!!!!
L3 L1 L2 L4 Comparative Brightness A. L1 and L3 are equally bright B. L3 is brighter than L1 C. L1 is brighter than L3 D. None of the above
L3 L1 L2 L4 Bulbs in Series and Parallel B. L3 is brighter than L1 The voltage across L3 is greater than the voltage across L1. Also, the current through L3 is greater than the current through L1
R1 = 3Ω R2 = 6Ω V = 12V Example 19.1 . . . Series Circuit Calculate the current flowing through the resistors voltage across the resistors power dissipation in the resistors
Req = 9Ω R1 = 3Ω R2 = 6Ω V = 12V V = 12V Solution 19.1 . . . Series Circuit Req = R1 + R2 I = 12/9 =4/3 A V1 = 4/3 x 3 = 4 V V2 = 4/3 x 6 = 8 V
R1 =6 Ω R2 = 3 Ω 12V Example 19.2 . . . Parallel Circuit Calculate the current flowing through the resistors voltage across the resistors power dissipation in the resistors
Req =2Ω R1 =6 Ω R2 = 3 Ω V = 12V 12V Example 19.2 . . . Parallel Circuit 1/ Req = 1/R1 + 1/R2 I1 = 12/6 =2 A I2 = 12/3 =4 A
R2 =6Ω R3 =4Ω R1 =3Ω V =12V Example 19.3 . . . Series /Parallel Combo Special! Calculate the current flowing through the resistors voltage across the resistors power dissipation in the resistors
R2 =6Ω Req =2Ω R3 =4Ω R3 =4Ω R1 =3Ω V =12V Solution 19.3 . . . Series /Parallel Combo Special! V =12V Ieq = 12/6 =2A Veq = 2 x2 = 4V V1 = V2 = 4V I1 = 4/3 A and I2 = 2/3 A
V A Ammeters and Voltmeters Voltmeter measures voltage Voltmeter is connected in parallel Voltmeter has a HIGH resistance Voltmeter is easy to hook up Ammeter measures current Ammeter is connected in series Ammeter has a LOW resistance Ammeter is tricky to hook up
C1 =6 F C2 = 3 F 12V Capacitors in Parallel Ceq = C1 + C2 V1 = V2 Q1 and Q2 may be different
C1 = 3 F C2 = 6 F V = 12V Capacitors in Series 1/Ceq = 1/C1 + 1/C2 Q1 = Q2 V1 and V2 may be different
V0 VR VC t RC Charging Circuit VC = V0 (1 - e -t /RC ) VR = V0 e -t /RC
RC Discharging Circuit VR =VC VC = V0 e -t /RC VR = V0 e -t /RC t