1. Lecture Name: Dr. Mohammed Elmaleeh Office Location: Building No. D Office Contact Number: 2933 e-mail: maleeho@hotmail.com ELECTRICAL CIRCUITS (EE 270)

2. Course Outlines Ohm’s Law Kirchhoff's Laws Resistors connections Circuit theorems:  superposition principle  Thevenin and Norton theorems  Maximum power transfer theorem

4. Course Grading Laboratory 20% Mid term115% Mid term215% Quizzes and assignments10% Final Exam40%

5. Electrical Engineering …………… Schume outline series …………. ……. References

6. Objectives of Lecture One To study Ohm’s Law To study the parallel and series connection of the resistors To understand the current flow in the parallel and serially connected resistors

7. Ohms Law V: Voltage (Volts) I: Current (Amps) R: Resistor (Ohm) It is the basic law concerning the flow of electricity. Ohm’s law states that when the electrical potential (voltage) creates a flow of electricity (current), the current and the electrical resistance of the circuit are proportional to the voltage.

9. Class Problems

10. To determine the current or voltage in a circuit that contains multiple resistors, the total resistance must first be calculated. Resistors can be combined in series or parallel. Resistors in circuits

11. Resistors in Series Sample Problem Calculate the total current through the circuit shown.

13. R 1, R 2 and R 3 are connected in series. R1R1 R2R2 R3R3 V I V = V 1 + V 2 + V 3 = I 1 R 1 + I 2 R 2 + I 3 R 3 = I (R 1 + R 2 + R 3 ) V1V1 V2V2 V3V3 I = current through R 1, R 2 and R 3 Equivalent resistance = IR T

14. R1R1 R2R2 R3R3 V I R (= R 1 + R 2 + R 3 ) I = I  (R 1 + R 2 + R 3 ) V= IR If two or more resistors are connected in series, the equivalent resistance is greater than any of each of the resistor

15. =6 V

16. When the resistors are connected in parallel the total resistor R T is given by: 1/R T = 1/R 1 + 1/R 2 + 1/R 3 + 1/R 4 1/R 5 +……. +1/R N The total resistor is smaller than any of the resistors that are connected in the circuit Parallel Resistors

17. R 1 R 2 R 1 + R 2 = R 1 || R 2 1 1 R 1 R 2 + 1 R eq = R1R1 R2R2 1 1 R 1 R 2 + 1 R eq =

18. R 1, R 2 and R 3 are connected in parallel. I2I2 I1I1 I3I3 R1R1 R2R2 R3R3 V I V = voltage across R 1, R 2 and R 3 I = I 1 + I 2 + I 3 = V R1R1 V R2R2 V R3R3 + + (1/R 1 + 1/R 2 + 1/R 3 ) V =

19. R1R1 R2R2 R3R3 V I1I1 I2I2 I3I3 I = I 1 + I 2 + I 3 1/R [= (1/R 1 + 1/R 2 + 1/R 3 ) V = I V R

21. From the circuit shown find the total resistor and the current through each resistor Example

22. Example: From the circuit shown: 1.Calculate the total resistor (equivalent resistor) 2.The current passing through each resistor 3.The voltage across each resistor