Lecture Week 4. Quiz 2 Ohm s Law Series Circuits Parallel Circuits Equivalent Circuits Workshop

Transcription

1 Lecture Week 4 Quiz 2 Ohm s Law Series Circuits Parallel Circuits Equivalent Circuits Workshop

2 Quiz 2 - Ohm s Law Please clear desks and turn off phones and put them in back packs You need pencil, straight edge and calculator 20 minutes Keep eyes on your own paper Follow same format as for homework

3 Series Circuit Series Circuits. How do I determine the current through each resistor? -Current is the same for all resistors How do I determine the voltage drop through each resistor? -Voltage is different for all resistors V Series Equivalent Resistance: Req = R 1 + R 2 + R 3 + Rn Image: Science Buddies Staff, Squishy Circuits Project 2: Add Even More Lights, [Online document], 11/21/15, [2/15/16], Available:

4 Series Circuit - Equivalent Circuit (1) Calculate the Equivalent Resistance (Req). Req = R 1 + R 2 + R 3 + Rn (2) Use Ohm s Law to determine the circuit current. I = V R eq (3) Then use Ohm s Law to determine the voltage drop across each resistor. V EQUIVALENT CIRCUIT CURRENT THROUGH ALL RESISTORS IS THE SAME AND EQUAL TO THE CIRCUIT CURRENT OF THE EQUIVALENT CIRCUIT V I Req V = IR 1

5 Parallel Equivalent Resistance I (1) Equivalent Resistance (Req) 1 R eq = 1 R R R n V EQUIVALENT CIRCUIT (2) Current through each Resistor using Ohm s Law I = V R eq I = I 1 + I 2 + I 3 (3) Voltage drop across each resistor V = V 1 = V 2 = V 3 -ALL RESISTORS IN PARALLEL EXPERIENCE THE SAME VOLTAGE DROP -EQUAL TO THE SUPPLY VOLTAGE OR POWER SUPPLY -CIRCUIT CURRENT IS SPLIT THROUGH EACH RESISTOR!!!

6 Parallel Resistance: Example EE 1305 Name Lab/Team # Date Problem Statement: Assuming you have two 1 k resistors in parallel, (a) determine the equivalent resistance, (b) the circuit current, (c) the current through each resistor, and (d) add up the currents through each resistor and compare to the circuit current. Equations/Unit Conversions 1 R eq = 1 R R R 3 + V = IR V = A Figures I 1 K 1 K Calculations: (a) 1 R eq = 1 R R 2 R eq = R 1R 2 R 1 + R 2 5V Req = 0.5 k R eq = 1 k 1 k (1 k + 1 k ) = 0.5 k

7 Parallel Resistance: Example con t EE 1305 Name Lab/Team # Date Calculations (b) V = IR eq I I = V R eq = 5 V 0.5 k 1 k 10 3 A V = 0.01 A 5V Req = 0.5 k (c) I = V R 1k = 5 V 1 k 1 k 10 3 A V = A Current through each resistor is 0.005A (d) I = A 2 = 0.01 A I 1 K 1 K Adding up the currents gives me the same current as the circuit current.

8 Shorthand Notation/Equivalent Circuits: Series Resistors Req = R1 + R2 + R3

9 Shorthand Notation/Equivalent Circuits: Parallel Resistors Req = R1 R2 R3

10 Shorthand Notation/Equivalent Circuits: Combination Resistors R = R2 R3 Req = R1 + R2 R3 + R4

11 Shorthand Notation/Equivalent Circuits: Example Simplify each side of the circuit.

12 Shorthand Notation/Equivalent Circuits: Example Combination of R3 and R5 Combination of R4 and R3 R5 Combination of R1 and R2

13 10 minute Break

14 Workshop

15 P2. Calculate the equivalent resistance for the resistors in series. Use the equivalent resistance to determine the current flowing through each resistor. Make sure to show the unit conversion V = AΩ when setting up your current (I) calculation. Show all units and unit conversions for each calculation.

16 P1. The circuit below includes 3 resistors in parallel, R 1 = 1kΩ, R 2 = 2 kω, and R 3 = 4 kω. (a) Determine the equivalent resistance (Req), (b) use Ohm s Law to determine the circuit current, (c) use Ohm s Law to determine the current through each resistor.

17 P3. (a) Simplify the circuit and determine the equivalent resistance. (b) Determine the circuit current, and(c) Determine the power consumed by the equivalent resistance and the power supplied by the 12 V source. (d) Does conservation of power exist in the circuit? Label each step and include units and unit conversions for full credit.

18 What s Next in Week 5? Will introduce LAB Module 1 Angle Sensor LECTURE Ohm s law and its applications: Voltage Divider Method Please bring laptops to all lectures and labs.

19 Questions?