PHYSICS SPRING 2015 Electric Circuits and Electric Current

PHYSICS SPRING 2015

Electric Circuits and Electric Current

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

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, 3.0C 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 12A. 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

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.How does a resistor effect the potential in a circuit?2.How does a battery effect the potential in a circuit?3.In terms of a battery, which end has high potential

and which end has a low potential4.Which direction does charge flow? (think potential)5.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 VΩmA hole and black plug in COM Dial should be turned to DCA 20m

When measuring voltage: The red plug in VΩmA 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 12.0V 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 .300Amps?

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 .0015C of charge to pass through the resistor every .010 ms. If the circuit is attached to a 9V 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 d155 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=rp8lwpvQEIM

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 the 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

1. How is totally current affected? Total current is constant through each resistor

ITOT = I1 + I2 + I3 …

2. How is resistance of the whole circuit affected?

Total resistance is the sum of all resistors in series.

Req = RTOT = R 1 + R2 + R3 + …+ 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:1. Calculate the Resistance and for each circuit.2. Answer the questions using the data on the following

slide The data goes in order of the lab and in order of

increasing number of resistors in a circuit.

Resistor # Manf. Resistance

Current (I) Voltage (V) Calculated Resistance

1 200 6A 1200V



1 200 3 560

2 240 3 690

Total XXXXXXXXX 3 1250



1 200 2 385

2 240 2 500

3 390 2 785

Total XXXXXXXXX 2 1700

One Resistor in Series

Two Resistors in Series

Three Resistors in Series



1 200 6A 1200V 200



1 200 3 560 186

2 240 3 690 225

Total XXXXXXXXX 3 1250 416



1 200 2 385 192

2 240 2 500 250

3 390 2 785 393






1. How is total current affected? Total current is constant through each resistor.

ITOT = I1 = I2 = I3 …

2. How is the voltage affected in a the circuit? The total voltage is the sum of all voltages in the

circuit.VTOT = V1 + V2 + V3 …

3. How is resistance of the whole circuit affected?

Total resistance is the sum of all resistors in series.RTOT = R 1 + R2 + R3 + …


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

VIR TABLESR I V

R1 10

R2 20

R3 30

Total 12V

Agenda 3/6/15

Warm-UP

Parallel Circuit Lab Findings from this lab

Notes on Parallel Circuits Practice Problems

VIR Tables: Parallel Circuits

PhET Activity: Building circuits

HW: Complete PhET


How does adding resistors affect the current?



Let’s Finish the lab

Using the data provided, complete the Ohm My, Parallelouusly Lab and analysis.



1 200 6A 1200V



1 200 5.5A 1200V 218

2 240 4.9A 1200V 245

Total XXXXXXXXX 11A 1200V 109



1 200 6.0A 1200V 200

2 240 5.1A 1200V 236

3 390 3.1A 1200V 387

Total XXXXXXXXX 13.9A 1200V 86.3

One Resistor

Two Resistors in Parallel

Three Resistors in Paralell



1 200 6A 1200V 200



1 200 3 560 186

2 240 3 690 225




1 200 2 385 192

2 240 2 500 250

3 390 2 785 393





Conclusions from the Parallel Lab

1. How is total current calculated in parallel? Total current is the sum of current through each resistor.

ITOT = I1 + I2 + I3 …

2. How is total voltage calculated in parallel? The total voltage is constant and equal to the battery’s

voltage.VTOT = V1 = V2 = V3 …

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/R2 + 1/R3 + …

Conclusions from the Parallel Lab

How does adding resistors affect the total current?



Let’s Practice

VIR TABLESR I V

R1 10

R2 20

R3 30

Total 12V

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 I V

BC 8

EF 3

GH 5

DI

JK 6

Total 12

BC DI JK: Series

Parallel: EF and GH

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 I V

R1 10

R2 20

R3 30

R3,2

R1,2,3

Rtot 120

Documents

PHYSICS SPRING 2015 Electric Circuits and Electric Current