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Electric Circuits and Electric Current PHYSICS SPRING 2015

Agenda 2/23/15 Go Over Potential Test Retake Policy Debrief circuit building White board pictures of circuits Notes on Circuit Drawing Current analogy HW: Finish Current Analogy

White Boards Each person needs a white board and a maker Take no more than 30 seconds and draw… A circuit with a battery and a light bulb A circuit with a battery and a toaster A circuit with a battery, a light bulb, a hair dryer and a T. V.

The Physics Way In order to keep things consistent, we have a certain way we draw each part of a circuit:

Try again… A circuit with a battery and a light bulb A circuit with a battery, a hair dryer and a T. V.

Agenda 2/23/15 Circuit Warm Up Current Demo Current Notes Concept and Equation HW: Current Problems

On a sheet of paper Draw a circuit with three resistors and one battery Remember that these have specific symbols

Definition of Current: The flow of electrical charge per unit time Equation: I = q/t Current is measured in units of AMPERES or amps

Example Problems In a current carrying wire, 3. 0 C of charge pass through a given point every. 02 seconds. What is the current in this wire?

Example Problems The current through a copper wire is 12 A. How much charge will pass through a point in this wire in a time of 10 seconds?

Example Problems An electron is traveling through a wire. One electron passes through a point in the wire every. 00500 seconds. What is the current in this wire?

Agenda 2/25/15 Parts of a circuit warm-up Recap Current Discovering Ohm’s Law Lab Concept and Equation Notes on Ohm’s Law Practice problems HW: Complete Ohm’s Law Lab/Practice Problems

Warm-UP On a half sheet of paper answer these questions: 1. 2. 3. 4. 5. How does a resistor effect the potential in a circuit? How does a battery effect the potential in a circuit? In terms of a battery, which end has high potential and which end has a low potential Which direction does charge flow? (think potential) Which direction do electrons flow?

Add to notes Current: Flow of charge in a circuit. Flows from high potential (+) to low potential (-). Opposite the flow of electrons Battery: This provides the “push” of charge in a circuit. Takes lowered potential and raises it back to voltage of battery Resistance: Items in a circuit that reduce or slow the flow of charge. Lower the potential in the overall circuit

Warm-UP A wire is carrying a current. At a point in this wire . 001 C of charge passes through in 3 ms. What is the magnitude of current in this wire?

Ohm’s Law Lab Safety: Do not touch the resistors when the battery source is producing a current. When modifying the circuit always return the battery source to O Volts. Tips: When measuring current: The red plug in the VΩm. A hole and black plug in COM Dial should be turned to DCA 20 m When measuring voltage: The red plug in VΩm. A and black plug in COM Dial should be turned to DCV 20 Always have the red pin on the red end of the resistor and the black end on the black end of the resistor

What is the resistance of your resistor?

Ohm’s Law An direct relationship between current and voltage. As voltage INCREASES current INCREASES (when resistance stays the same) An indirect relationship between current and resistance. As resistance increases, current decreases (when voltage stays the same) Equation: V=IR V= voltage (Volts) I = current (Amps) R= resistance (Ω, ohms)

Practice Problem What is the current in a circuit that has a power supply of 12. 0 V and a resistor with a resistance of 100. 0Ω?

Practice Problem What is the voltage of a battery if the current through a circuit containing a 15Ω resistor is. 300 Amps?

Agenda 2/26/15 Current/Resistance Warm-up Review HW Recap Discovering Ohm’s Law What relationships exist? Intro Power Lab Ohm’s Law Practice problems HW: Complete Ohm’s Problems, Get Power Meter Reading

Practice Problem A circuit containing a battery and a resistor allows . 0015 C of charge to pass through the resistor every. 010 ms. If the circuit is attached to a 9 V battery, what is the resistance in the resistor?

Discovering Ohm’s Law Let’s Recap What did we do in the lab yesterday? What did we measure? What was held constant? What shape did our graph take? What was our x variable? What was our y variable? What did the slope represent? What can we take away from this lab about the relationship between V, I and R?

Power Lab Tomorrow we will discuss power. This weekend you are to explore the different appliances you use in your house to determine how much power you are consuming. Tonight it is your job to find out where the electrical meter is and take a baseline reading. On Sunday you will do the same to determine the overall consumption of electrical energy you used this weekend.

Agenda 2/27/15 Check HW assignment Initial if power reading taken Current and resistance exit slip Introduction Activity to Power Physics Classroom Intro Power Lab Power Practice problems HW: Complete Power Lab Data table

Agenda 3/2/15 Check Power Lab Data Table Discuss the mathematical portion of this lab Solve for energy usage and complete discussion questions Follow-up Activity (Going Green) Research viable alternatives HW: Complete a personal conclusion discussing the changes you would make to your home.

Going Green Using a Chromebook: Research viable alternatives to replace items in your home Determine how much power and current these items draw Determine how much money these items could save you over the course of a year. This research will be summarized in a personal conclusion that will be turned in on Wednesday. Conclusions should be long enough to clearly identify the changes you are making and the reasons why you are making these changes. **I will post this assignment to My Announcements on my d 155 webiste

Agenda 3/4/15 Collect Power Lab/Assignment Hand out equation sheets Power and Voltage warm-up Introduction to types of circuits Video Clip Ohm My Serious Lab Series Notes and Practice HW: Complete the Lab analysis questions

Warm-Up Complete #1 -4 on the Power and Energy WS Check with a partner near you once you are complete ** Practice using your equation sheet

Types of Circuits The first type of circuit…the annoying circuit https: //www. youtube. com/watch? v=rp 8 lwpv. QEIM THE SERIES CIRCUIT

OHM My Seriously Lab Safety: Do not touch the alligator clips when the power supply is on. Only take measurements the way it is described in the lab. Tips: Keep the power supply at the same voltage during each setup. If you need to adjust wires, unplug the supply, don’t dial it down. Complete three setups first and worry about the calculations later. **First determine the resistance in your resistors

What is the resistance of your resistor? • The first two bands are digits • The third band is the multiplier

Conclusions from the Series Lab How is totally current affected? 1. Total current is constant through each resistor ITOT = I 1 + I 2 + I 3 … 2. How is resistance of the whole circuit affected? Total resistance is the sum of all resistors in series. Req = RTOT = R 1 + R 2 + R 3 + …+ Rn

Agenda 3/5/15 Warm-UP Series Circuit Lab Revisit the Lab Notes on Series Circuits Practice Problems VIR Tables HW: Complete the Series Practce

Warm-Up Complete #5 -8 on the Power and Energy WS Don’t forget to use your equation sheet!!

Let’s Finish the lab Using your analysis from the lab: Calculate the Resistance and for each circuit. Answer the questions using the data on the following slide 1. 2. The data goes in order of the lab and in order of increasing number of resistors in a circuit.

One Resistor in Series Resistor # Manf. Resistance Current (I) Voltage (V) 1 200 6 A 1200 V Two Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) 1 200 3 560 2 240 3 690 Total XXXXX 3 1250 Three Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) 1 200 2 385 2 240 2 500 3 390 2 785 Total XXXXX 2 1700 Calculated Resistance

One Resistor in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 6 A 1200 V 200 Two Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 3 560 186 2 240 3 690 225 Total XXXXX 3 1250 416 Three Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 2 385 192 2 240 2 500 250 3 390 2 785 393 Total XXXXX 2 830 835

Conclusions from the Series Lab How is total current affected? 1. Total current is constant through each resistor. ITOT = I 1 = I 2 = I 3 … 2. How is the voltage affected in a the circuit? The total voltage is the sum of all voltages in the circuit. VTOT = V 1 + V 2 + V 3 … 3. How is resistance of the whole circuit affected? Total resistance is the sum of all resistors in series. RTOT = R 1 + R 2 + R 3 + …

Conclusions from the Series Lab How does adding resistors affect the current? How does adding resistors affect the voltage? How does adding resistors affect the overall resistance?

Let’s Practice R R 1 20 R 3 V 10 R 2 I VIR TABLES 30 Total 12 V

Agenda 3/6/15 Warm-UP Parallel Circuit Lab Findings from this lab Notes on Parallel Circuits Practice Problems VIR Tables: Parallel Circuits Ph. ET Activity: Building circuits HW: Complete Ph. ET

Conclusions from the Series Lab How does adding resistors affect the current? How does adding resistors affect the voltage? How does adding resistors affect the overall resistance?

Let’s Finish the lab Using the data provided, complete the Ohm My, Parallelouusly Lab and analysis.

One Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 6 A 1200 V Two Resistors in Parallel Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 5. 5 A 1200 V 218 2 240 4. 9 A 1200 V 245 Total XXXXX 11 A 1200 V 109 Three Resistors in Paralell Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 6. 0 A 1200 V 200 2 240 5. 1 A 1200 V 236 3 390 3. 1 A 1200 V 387 Total XXXXX 13. 9 A 1200 V 86. 3

One Resistor in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 6 A 1200 V 200 Two Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 3 560 186 2 240 3 690 225 Total XXXXX 3 1250 416 Three Resistors in Series Resistor # Manf. Resistance Current (I) Voltage (V) Calculated Resistance 1 200 2 385 192 2 240 2 500 250 3 390 2 785 393 Total XXXXX 2 830 835

Conclusions from the Parallel Lab How is total current calculated in parallel? 1. Total current is the sum of current through each resistor. ITOT = I 1 + I 2 + I 3 … 2. How is total voltage calculated in parallel? The total voltage is constant and equal to the battery’s voltage. VTOT = V 1 = V 2 = V 3 … 3. How is total resistance calculated in parallel? The inverse of the total resistance is the sum of the inverse of each resistor. 1/RTOT = 1/R 1 + 1/R 2 + 1/R 3 + …

Conclusions from the Parallel Lab How does adding resistors affect the total current? How does adding resistors affect the voltage? How does adding resistors affect the overall resistance?

Let’s Practice R R 1 20 R 3 V 10 R 2 I VIR TABLES 30 Total 12 V

Agenda 3/10/15 Grab an Nspire Login to our network Complete the Circuit Activity Series and Parallel exit slip HW: None

Nspire info Settings Login Network 2 Username: firsinitiallastname Example: sclause PW: lastname Example: clause

Agenda 3/11/15 Review Lab Findings Turn in lab Nspire brainstorm and reflection Series and Parallel Exit Slip Combo Circuits Notes and Practice HW: Combo Circuits

What kind of circuit is this?

Combo Circuit Let’s complete a VIR Table for the entire circuit.

R BC 3 GH V 5 BC DI JK: Series 8 EF I Parallel: EF and GH DI JK Total 6 12

Agenda 3/11/15 Combo Circuit Warm-UP Hand back exit slips Nspire Review Questions Due by end of class for points HW: Complete the Review Guide for Circuits Unit

Combo Circuit R R 1 20 R 3 V 10 R 2 I 30 R 3, 2 R 1, 2, 3 Rtot 120