Lecture Week 5 Voltage Divider Method Equivalent Circuits Review Lab Report Template and Rubric Workshop
Voltage Divider Method The voltage divider is a method/tool that can be used to: Design voltage inputs Analyze and/or simplify complex circuit When analyzing a circuit, always determine if the voltage divider method can be used to simplify a circuit!!
Voltage Divider Method The voltage divider relates the total voltage to the potential drop across one of the resistors. R eq = R 1 + R 2 I = V s R eq = V s R 1 +R 2 V 1 = I R 1 = V s R 1 + R 2 R 1 = Vs R 1 R 1 + R 2 v i = v s R i R eq V 2 = I R 2 = V s R 1 + R 2 R 2 = Vs R 2 R 1 + R 2 VOLTAGE DIVIDER METHOD VERY POWERFUL TOOL USED TO ANALYZE CIRCUITS!!!
Voltage Divider Method: Exercise 1 Determine the voltage drop across BOTH R 1 and R 2, based on the following component values: Vs = 5 V, R 1 = 1 M, and R 2 = 725 k v i = v s R i R eq TIP: IN THIS CASE, IT HELPS TO CONVERT YOUR UNITS TO OHMS ( ) BEFORE PLUGGING IN VALUES INTO EQUATION.
Voltage Divider Method: Exercise 2 Assume R1, R2, R3 and R4 are all equal to 121. (a) Determine the equivalent resistance for R3 R5 based on the 3 values for R5 listed in the table below. (b) Use the Voltage Divider method to determine the voltage drop across R4 based on R3 R5 equivalent value. R5, R3 R5, Voltage Drop Across R4, V 100,000 499,000 1,000,000
Voltage Divider Method: Analyzing Exercise 2 What happens to the value of R3 R5 as R5 is increased? Complete this statement: When there are two resistors in parallel, and on of those resistors increased, the equivalent resistance. [INCREASES/DECREASES] R5, R3 R5, 100,000 499,000 1,000,000
Voltage Divider Method: Analyzing Exercise 2 What happens to the value of R4 as R5 is increased? Complete this statement: When R5 is increased, the equivalent resistance of R3 R5 [INCREASES/DECREASES], and the voltage drop across R4. [INCREASES/DECREASES] R5, R3 R5, 100,000 120.8538 499,000 120.9707 1,000,000 120.9854 v i = v s R i R eq
Voltage Divider and Shorthand Notation: Exercise 3 (a) Simplify the circuit below using equivalent parallel/series resistance and voltage divider to determine V A. As you simplify the circuit, RE-SKETCH the equivalent circuit and label the equivalent resistor values using SHORTHAND NOTATION. (b) Determine the current through R 3 ( I 3 ) V in = 5 V R 1 = 125 Ω R 2 = 220 Ω R 3 = 500 Ω
LAB REPORT HIGHLIGHTS Lab Report Template..\Lab Report Template_SP19.doc Lab Report Rubric..\Lab Report Rubric_SP19.doc
10 minute Break
Workshop
P1 (a) Simplify the circuit below using equivalent parallel/series resistance and voltage divider to determine V A and V B. As you simplify the circuit, RE- SKETCH the equivalent circuit and label the equivalent resistor values using SHORTHAND NOTATION. (b) Determine the current through R 2 ( I 2 ) V in = 10 V R 1 = 125 Ω R 2 = 220 Ω R 3 = 500 Ω R 4 = 100Ω
P2 (a) Use the shorthand notation/equivalent circuit method to reduce the circuit until there are only 2 resistors left. For each step, show the equivalent circuit, and write the shorthand notation expression. (b) (b) When there are only 2 resistors left, determine the expression for the voltage drop at V A using the voltage divider method. Make sure to include the equation for voltage divider at the beginning of this step.
Voltage Divider and Shorthand Notation - Solutions
P3 (a) Determine the circuit total current (I T ) for the simplified circuit in P2 if R1 R4 are equal to 100Ω and V in is equal to 9 V. (b) Use Ohm s Law to confirm the voltage drop at V A. (c) Use the expression for P2 part (b) to determine V A using the voltage divider method. Show every step, units, and unit conversions for full credit.
What s Next in Week 6? Will introduce LAB Module II Strain Gauge LECTURE Quiz 3 Ohm s Law and Voltage Divider Kirchhoff's Laws Please bring laptops to all lectures and labs.
Questions?