1. Announcements  Homework for tomorrow… Ch. 31: CQ 6, Probs. 8, 11 & 16 30.24: 1/2 30.53: a) (10 A)e -t/(2.0s) b) I(t = 0) = 10 Ac) plot of exponential decay 30.56: 5.6 x 10 -6 m/s  Office hours… MW 12:30-1:30 pm TR 9-10 am F 1-2 pm  Tutorial Learning Center (TLC) hours: MW 8-10 am, 12-6 pmR 8-12 pm, 2-6 pm T 8-1 pm, 2-6 pmF 8-10 am, 2-5 pm

2. Chapter 31 Fundamentals of Circuits (Series Resistors & Real Batteries)

3. Rate at which the battery supplies energy to the charges is.. Review…

4. Power dissipated by a resistor.. 31.3: Energy and Power

5. Power dissipated by a resistor.. Notice: For resistors in series, the resistor with the largest resistance dissipates the most power. For resistors in parallel, the resistor with the smallest resistance dissipates the most power. 31.3: Energy and Power

6. Which resistor dissipates more power? 1. The 9  resistor. 2. The 1  resistor. 3. They dissipate the same power. Quiz Question 1

7. Most loudspeakers are designed to have a resistance of 8Ω. If an 8Ω loudspeaker is connected to a stereo amplifier with a rating of 100W, what is the maximum possible current to the loudspeaker? i.e. 31.4: The Power of Sound

8. The energy dissipated by a resistor during time interval Δt is 1 kW  h is equivalent to how many J’s? How long does it take for a 14 W c.f.l. to ‘consume’ this much energy? Kilowatt Hours

9. How does the brightness of bulb B compare to that of bulb A? 1. Bulb B is brighter. 2. Bulb A is brighter. 3. Both bulbs have the same brightness. Quiz Question 2

10. Consider two resistors in series…  Can we find an equivalent resistor, R eq, to the two resistors, R 1 & R 2 ? 31.4: Series Resistors + - R1R1 R2R2 + - R eq

11. Consider two resistors in series…  Can we find an equivalent resistor, R eq, to the two resistors, R 1 & R 2 ?  YES! 31.4: Series Resistors + - R1R1 R2R2 + - R eq

12. What about several resistors in series…  Can we find an equivalent resistor, R eq, to the resistors, R 1, R 2,…(all in series)? 31.4: Series Resistors + - R1R1 R2R2 + - R eq R3R3

13. What about several resistors in series…  Can we find an equivalent resistor, R eq, to the resistors, R 1, R 2,…(all in series)?  YES! 31.4: Series Resistors + - R1R1 R2R2 + - R eq R3R3

14. a. What is the current in the circuit below? b. Draw a graph of potential versus position in the circuit, going cw from V = 0V at the battery’s negative terminal. i.e. 31.5: A series resistor circuit

15.  are used to measure currents.  Must be wired in series with the circuit element whose current is to be measured.  R ammeter ~0 Ω Ammeters…

16.  have an internal resistance, r  The terminal voltage is… Notice:  only when I = 0, is. 31.5: Real Batteries