1. Electric C ircuit -Is a complete or closed path through which charge can flow from one terminal of an electric source (battery) to the other. 4 main components: 1.One that drives electric charge round the circuit 2.One on which the moving charge can be useful 3.Conductors 4.switches

2. Two Basic Methods of Connecting Electrical Components Series CircuitParallel Circuit

3. Series Circuit The current flow is the same throughout the lamp. ( I =I 1 = I 2 = I 3 ) The total combined resistance is equal to the sum of the individual resistances. (R = R 1 + R 2 + R 3 ) The total voltage is equal to the sum of the individual voltages across the resistors. ( V TOT = V 1 + V 2 + V 3 )

4. Parallel Circuit The voltage across each lamp is equal to the voltage applied. The total current is the sum of the currents in the separate branches. I tot = I 1 + I 2 + I 3 The total combined resistance is given by 1/R tot = 1/R 1 + 1/R 2 + 1/R 3

5. Example Problems 1.Four 15-Ω resistor are connected in series with a 45- V battery. What is the current in the circuit?

6. Solution Given: V= 45 v R 1 = R 2 = R 3 = R 4 = 15 Ω I= V/R eq ; R eq =R (1+2+3+4) = 15Ω(4) = 60 Ω I= 45 v/ 60 Ω = 0.75 A

7. Example Problem 2 V = 40 v R 1 = 20 Ω R 2 = 15 Ω R 3 = 10 Ω I 1, I 2, I 3 = ? Sol’n. 1/R eq = 1/20 + 1/15 + 1/10 R eq = 4.55 Ω I 1` = V tot / R 1 = 40V/20Ω = 2 A I 2 = 40V/15Ω = 2.67 A I 3 = 40 V/ 10Ω = 4 A

8. Analysis of Combined Circuit

9. This method is consistent with the formula 1/R tot = 1/R 1 + 1/R 2 + 1/R 3 where R 1, R 2, and R 3 are the resistance values of the individual resistors that are connected in parallel. If the two or more resistors found in the parallel branches do not have equal resistance, then the above formula must be used.

10. Equivalent circuit

11. a. The current at location A is _____ (greater than, equal to, less than) the current at location B. b. The current at location B is _____ (greater than, equal to, less than) the current at location E. c. The current at location G is _____ (greater than, equal to, less than) the current at location F.

12. d. The current at location E is _____ (greater than, equal to, less than) the current at location G. e. The current at location B is _____ (greater than, equal to, less than) the current at location F. f. The current at location A is _____ (greater than, equal to, less than) the current at location L. g. the current at location H is _____ (greater than, equal to, less than) the current at location I.

13. Problem 1.