Reading Quiz A light bulb is connected to a battery so that current flows through the bulb, which gives off light. Choose the correct statement: The amount of current going into the bulb equals the current leaving the bulb. The amount of current entering the bulb is greater than the amount of current leaving the bulb. The bulb is converting electric charge into light.

Physics Help Center NEXT EXAM Wednesday April 7th @7pm to 9pm Room 237 Physics Building: 8am to 5:30pm Ask for help from graduate students on homework and exams Can enter solutions on the computers in the room to check your solution. NEXT EXAM Wednesday April 7th @7pm to 9pm Chapters 10,11,12,13,14,15

Summary of electric circuits: The amount of current is the same at every place in a series circuit; I=q/t. The power provided by the battery (P=IDV) is exactly equal to the power dissipated in the resistors (P=I2R). Ohm’s Law applies to resistors: DV=IR Series circuit: effective R = R1 + R2 + R3 Parallel circuit: effective R is

Fig. 13.3 Fig. 13.3

Fig. 13.1 Fig. 13.1

Fig. 13.2 Fig. 13.2

Fig. 13.4 Fig. 13.4

Summary 2 Fig. 13.p270b

Ohm’s Law applies to resistors: DV=IR Battery increases energy of charges (DPE); voltage on battery is called “EMF”. This amount of energy is expended in the resistor. For a given battery (V) and resistor (R), the current is given by Ohm’s Law: DV=IR EMF volts I V R The unit of resistance is an Ohm.

Fig. 13.6 Fig. 13.6

Fig. 13.7 Fig. 13.7

Fig. 13.5 Fig. 13.5

A simple battery does which of the following: Lecture Quiz 26 - Question 1: A simple battery does which of the following: A. It creates charges. B. It does work on charges. C. It creates energy.

Is the voltage drop the same across all three resistors? Series Resistance EMF= DV1 + DV2 + DV3 OR V = IR1 + IR2 + IR3 = I(R1 + R2 + R3) = I Rseries Where Rseries = R1 + R2 + R3 EMF volts R1 V R2 R3 Is the voltage drop the same across all three resistors? Is the current the same through all three resistors?

Fig. 13.9 Fig. 13.9

What is the total resistance of this circuit? Exercise 9 What is the total resistance of this circuit? 1.) 66 ohms 2.) 60 ohms 3.) 54 ohms 4.) 25 ohms 5.) 15 ohms Fig. 13.p274a

What is the current that flows in this circuit? Exercise 9 What is the current that flows in this circuit? 1.)10 amps 2.) 1 amp 3.) 0.1 amp 4.) 0.3 amp 5.) 0.03 amps Fig. 13.p274a

Fig. 13.10 Fig. 13.10

V = I Reffective Parallel Resistors Effective resistance 1 2 3 V Where EMF volts 1 2 3 V Where V = I Reffective How much current flows through the three resistors? Is the voltage drop the same for all three resistors?

Exercise 12 What is the total resistance of this circuit? 1.) 72 ohms Fig. 13.p274b

A . What is the current that flows in this circuit at point A? 1.)288 amps 2.) 1.5 amp 3.) 0.1 amp 4.) 0.5 amp 5.) 0.03 amps Fig. 13.p274b

B. What is the current that flows in this circuit at point B? 1.)288 amps 2.) 1.5 amp 3.) 0.1 amp 4.) 0.5 amp 5.) 0.03 amps Fig. 13.p274b

By placing electrical items in series they receive the same current By placing all electric items in parallel they receive the same voltage Fig. 13.19 By placing electrical items in series they receive the same current

A volt meter has a high resistance so take very little current Fig. 13.12 A volt meter has a high resistance so take very little current

Fig. 13.13 Fig. 13.13 An Amp meter has very little resistance so take very little voltage

Summary of electric circuits: The amount of current is the same at every place in a circuit; I=q/t. The power provided by the battery (P=IDV) is exactly equal to the power dissipated in the resistors (P=I2R). Ohm’s Law applies to resistors: DV=IR Series circuit: effective R = R1 + R2 + R3 Parallel circuit: effective R is

Question 14 Fig. 13.p272g

For an “ohmic” resistor, V=IR, so P = I2R The power provided by the battery (P=IDV) is exactly equal to the power dissipated in the resistors (P=I2R). Power P= work/time Power=DPE/t =qDV/t =IDV =IV For an “ohmic” resistor, V=IR, so P = I2R

Lecture Quiz #26 Question 2 Consider a standard flashlight which is turned on. A. The batteries create electrons, which get used up in the light bulb. B. Energy is created in the batteries, which is destroyed in the light bulb. C. The power used up by the light bulb originates in the batteries. D. The light bulb converts electrons into light.

Lecture Quiz: Question 3 How much current I runs through this circuit: A. 0.25 Amps B. 0.375 A C. 0.67 A D. 1.50 A E. 2.25 A 3 V 4 W 4 W

Lecture Quiz: Question 4 For three resistors in parallel, choose the correct statement: A. The current and the voltage across all three are the same. B. The voltage drop and the power dissipated across all three are the same. C. The energy given up per electron is the same for all three. D. The current through one resistor is the same as the current through the battery. EMF volts 1 2 3

What does the battery do? Where does the light energy come from? The amount of current is the same at every place in a (single-loop) circuit; I=q/t. I Battery Light Bulb I I What does the battery do? Where does the light energy come from? Why do batteries burn out? I