Retention Assessment n Put your books away and

Retention Assessment n Put your books away and take out a sheet of paper. Answer the questions below to the best of your ability. n When you have finished, fold your paper in half and raise your hand to have your paper collected. n Your score will count toward In-Class activities EGR 101 1

Quiz n 1. What is the relationship between current and charge? n 2. Express voltage in terms of charge, energy, and/or time. n 3. Express Power in terms of charge, energy, and/or time. n 4. State Ohm’s Law. EGR 101 2

Today’s Agenda Chapter 4 Series Circuits Voltage Divider EGR 101 3

Series Circuit n Series Circuit – a circuit that contains only one current path EGR 101 4

Series Circuit Characteristics n Current Characteristics – the current through any element in a series circuit must equal the current through every other element in the circuit EGR 101 5

Series Connections n Two elements are connected in series if ALL of the current of one element flows through the second. n Which of the following are in series? A B C D E F EGR 101 6

Relation to Lab Activity n In the lab last week, for one of the circuits, you had 2 resistors connected as shown to the right (with different values) and a meter set on Ohms measuring them. Are the resistors in series? n What resistance would the multimeter read if you built this circuit? n What would the meter read if you put 10 22 k-Ohm resistors in series? EGR 101 7

Series Connection Characteristics n Total Series Resistance where RT = the total series resistance Rn = the highest-numbered resistor in series EGR 101 8

Example Series Circuit V 1 V 2 • What is the total resistance? • What is the current, IT? • What is the voltage across each resistor? EGR 101 9

Kirchhoff’s Voltage Law n Note, in the example on the previous page, Vs = V 1 +V 2 EGR 101 10

Series Circuit Characteristics n Series circuits have the following voltage characteristic: where VS = the source (or total supply) voltage Vn = the voltage across the highest numbered resistor in the circuit EGR 101 11

Voltage Relationships n Kirchhoff’s Voltage Law q q The sum of the component voltages in a series circuit must equal the net source voltage 1840 – German Physicist, Gustav Kirchhoff EGR 101 12

Series Circuit Characteristics n Power Characteristics where PS = the source power PT = the total power dissipated by the circuit Pn = the power that is dissipated across the highest numbered resistor in the circuit EGR 101 13

Team Activity # 1: Refer to Figure 4. 45(d) on p. 125 of textbook Method 1: q q q Calculate the total resistance of the circuit, RT. Calculate I using RT and Ohm’s Law. Calculate the total power PT using Vs and I. Method 2: q q q Calculate I using Ohm’s Law. Calculate the voltage across each resistance, V 1, V 2, V 3 & V 4. Calculate the power in each resistor P 1, P 2, P 3 & P 4. EGR 101 14

Comparison of Results n Questions: q q Does the VT you computed in Method 2 equal Vs from Method 1? Does the sum of P 1, P 2, P 3 & P 4 equal PT from Method 1? EGR 101 15

Voltage Notations n n Single subscript, VA – indicates the voltage is measured from the specified point relative to ground A + _ + Two subscripts, VAB – indicates the voltage is measured from the first identified point to the second A _ + B _ EGR 101 } } } VA VAB V? 16

Voltage Divider n The Voltage Divider Relationship – Often used to analyze a portion of a series circuit A n Allows us to determine individual voltages Rest of Circuit B EGR 101 } } } V 1 V 2 V 3 17

Voltage Divider Relation n For a series combination of N resistors with Vs (VAB in previous slide) applied across them, the voltage across Rn is: where Rn = the resistor n of interest Vn = the voltage across Rn RT = the total series resistance EGR 101 18

Team Activity # 2: Refer to Figure 4. 46(c) on p. 125 of textbook 1. 2. 3. 4. 5. Calculate the voltage across each resistor, R 1, R 2, & R 3 by the Voltage Divider Method. What is the resistance from point A to ground? Calculate the current through each resistor using your results from step 1. Calculate the current in the circuit based on Vs and total resistance. Do your results from steps 3 and 4 agree? EGR 101 19

The Potentiometer as a Voltage Divider n Audio Amplifier Application EGR 101 20

Team Activity # 3: Refer to Figure 4. 39(b) on p. 122 of textbook q Solve problem 12. EGR 101 21