Grade: 9-12

Content Area: Science

Course Name: Physics

Description of Unit: In this unit students will explore both static and current electricity. There are expanded activities for circuits. Magnetism will also be part of the unit and student’s will tie both concepts together with electric motors.

Approximate Time Needed: 13-15 days

Lesson

Duration

Supporting Target

Resources

Assessment

1

3-4 days

I can explain why currents flow when free charges are placed in an electric field, and how that forms the basis for electric circuits.

I can describe how an electric current produces a magnetic force, and how this interaction is used in motors and electromagnets to produce mechanical energy.

Electrostatic Exploration 

Electrostatic Presentation

Coulomb’s Law Lab

Electric Field Lab

Pre

Formative

2

2-3 days

I can explain and calculate current, voltage and resistance, and describe energy transfers in simple electric circuits.

I can explain and calculate the relationship of current, voltage, resistance and power in series and parallel circuits. 

Building Simple Circuits

Circuit Introduction

Ohm’s Law Lab

Pre

Formative

3

1 day

I can explain and calculate current, voltage and resistance, and describe energy transfers in simple electric circuits.

I can explain and calculate the relationship of current, voltage, resistance and power in series and parallel circuits.

Electric Circuits Worksheet

Formative

4

1 day

I can explain and calculate the relationship of current, voltage, resistance and power in series and parallel circuits.

Series and Parallel Lab

Formative

5

3 days

I can describe general properties of magnetism.

I can describe how an electric current produces a magnetic force.

Magnetic Properties Exploration

Magnet Introduction

Electromagnet Lab

Pre

Formative

6

1 day

I can describe general properties of magnetism.

I can describe how an electric current produces a magnetic force.

Magnetism Worksheet

Formative

7

1 day

I can identify the energy forms and explain the transfers of energy involved in the operation of common devices. For example: Electric motors. I can describe how moving electric charges produce magnetic forces.

Electric motor construction

Summative

8

1 day

All standards

Fictional Physics - Hover Shoes

Project Rubric

Summative

Activity

Notes to Instructors

Electrostatic Exploration

Purpose: This exploration can be done after the Electrostatic Presentation or it can be intermixed with the presentation (as shown in notes to instructors for Electrostatic Presentation below).

Part A: Step 3 - Attractive interaction: As the tape was pulled from the table it became charged, which caused it to attract to the neutral paper.

Part B: Step 3 - Repulsive interaction: As the tape was pulled from the table it became charged. All three strips of tape had the same charges, so they repelled one another.

Part C: Step 1 - Nothing happens; leaves do not move.

       Step 2 - Leaves move apart.

       Step 3 - Rubbing the comb or balloon caused it to gain electrons, giving it a negative charge. When it touched

              electroscope, the electrons on the electroscope were attracted to the object, and moved up the  

              electroscope. This left the leaves of the electroscope with positive charges, so they repelled one                                  

              another.

       Step 4: Same results as step 3.

Discussion question 1: Rubbing the balloon or comb.

Discussion question 2: Touching the balloon or comb to the electroscope.

Discussion question 3: Holding the tape above the pieces of paper; holding the balloon or comb near the electroscope.

Time: 50 minutes

Electrostatic Presentation

Slide 2: The procedure of the Electrostatic Exploration can be completed at this time. Encourage students to consider their results as you continue the Electrostatic Presentation.

Slide 4: The wool becomes positively charge, and the rubber becomes negatively charged.

Slide 5: The discussion questions of the Electrostatic Exploration can be completed at this time.

Coulomb’s Law Lab

Purpose: To use Coulomb’s law to demonstrate electric force between two charged objects.

Data and Analysis:

 Values will vary:

1. The distance in the second trial was larger than the distance in trial one. Rubbing the balloons more resulted in a greater charge.

2. Electric force and the force of gravity (weight).

3. Students should use the force of gravity (weight) for the electric force in Coulomb’s equation. Since it is assumed that both balloons have the same charge, the equation can be modified to; F = (k x q2)/r2.

For the sample data: rubbed 3 times; 7.9 x 10-8 C and rubbed 10 times; 6.5 x 10-7 C.

4. Students should use the charge for the balloons for each trial and divide it by 1.60 x 10-19 C.

For the sample data: rubbed 3 times; 4.9 x 1011 electrons and rubbed 10 times; 4.1 x 1012 electrons.

Discussion:

1. Both balloons gain electrons when charged by friction, so they repel one another.

2. The leaves would move apart because the balloon has a charge.

3. Both balloons were not equally charged, distances were difficult to measure so it might not be accurate, calculation errors.

Time: 50 minutes

Electric Field Lab

Purpose: To become familiar with electric forces and electric fields.

This is an optional lab, as it requires Java.

Data Table 1: Answers will vary based on how many arrows the students draw, however arrows should be drawn away from all positive charges and towards all negative charges.

Data Table 2: Electric Field Measurements for a Positive Charge

Data Table 3: Electric Field Measurements for a Negative Charge

Data Table 4: Electric Field Measurements for a Positive Charge and a Negative Charge

Analysis and Conclusions:

1. Electric fields are always away from a positive charge and towards a negative charge.

2. The magnitude of the electric field strength is the same at the same coordinates for a charge of equal magnitude, regardless if the charge is positive or negative.

3. The direction of the electric field is opposite for opposite charges.

4. The electric field strength is greatest near either charge. The direction of the electric field is still away from the positive charge and towards the negative charge.

Optional Challenge: The electric field strength is inversely related to the square of the distance from the source. The graph should represent the inverse square law.

Time: 60 minutes

Building Simple Circuits

Purpose: Power resistors work well for this, especially if you decide to use a battery charger to supply the voltage. A three conductor cable can be attached to the terminals of the charger and wires exposed at various intervals and allow multiple lab stations access to a voltage source without the hassle of replacing batteries.

Key:

1. They are the same.

2. The ammeter can be located anywhere in a simple circuit to measure the current in the circuit as it is the current is the same throughout.

3. They are the same.

4. There was more current in the circuit when R1 was in the circuit than when R2 was in the circuit.

5. R2 has more resistance than R1.

Time: 60-80 minutes

Circuit Introduction

Purpose: Covers some of the basic concepts centering on circuits, conductors, insulators, switches, resistors, resistance and voltage.

Time: 30 minutes

Ohm’s Law Lab

Purpose: To understand the relationships of amps, volts and ohms in an electrical circuit.

Two multimeters are required for each student group.

1. All calculated resistances are about the same for R1.

2. The resistor has a fixed amount of resistance.

3. Approximately 10 ohms.

4. Approximately 20 ohms.

5. R2 has about twice the resistance of R1.

6. Slope is the resistance.

7. R1 = 10 and R2 = 20

8. It varies overall resistance in the series circuit. More resistance means less current. More resistance on the rheostat means less voltage drop across the fixed resistor.

Time: 60 minutes

Electric Circuits Worksheet

Key

1. a) 1.2 Ω b) 7 Ω c) 14 Ω

2. total resistance = 5.5 Ω, all voltages are 6 v and currents are 0.6 amp, 0.3 amp, 0.2 amp and 1.1 amp

3. total resistance = 22 Ω, total current & 1 = 0.27 amp, current for 2 = 0.16 amp, current for 3 = 0.11 amp, voltage for 1 = 2.7 v, voltage for 2&3 = 3.3 v

4. 240 Ω

5. 190 Ω

6. 2.4 Ω

7. 4 amp

8. 12 Ω

Series and Parallel Lab

Purpose: This lab will compare the concepts of voltage, current and resistance in both series and parallel circuits with experimental data.

Materials: Multimeters are required for this lab. They are used to measure the resistance, voltage and current. If you have extra meters or probes that measure voltage and current, you could decrease the student’s time in data collection.

Ceramic resistors between 100 Ω and 1000 Ω should be used. Small zip lock bags can be used to set up the three resistors and make them unique for each experiment. Create enough bags for 2 more than the number of groups that you have and label the bags.

A power supply can be used if you have them available. 6 volt lantern batteries will also work.

Analysis: In all cases, the data should match the concepts very closely. Use this as your check for understanding.

Time: 50 minutes

Magnetic Properties Exploration

Magnet Introduction

Purpose: Introduce students to general properties of magnetism.

Materials: (per group) 2 magnets, set of 6 test objects, iron filings in petri dish, battery, 2 wires, light bulb, compass

The introduction is designed to be done in conjunction with the exploration activities. For the test objects, make sure that you have some things that are magnetic and some that are not, including nonmagnetic metal samples as students commonly believe that all metals are magnetic.

Activity Key:

Part 1 Questions:

1. Answers will vary, but most students are wrong about the nonmagnetic metals.

2. Both can attract/repel objects over a distance.

3. Can’t discharge magnets, magnets do not work with as wide variety of objects…

4. Magnets can only be repelled by other magnets and nothing else.

Part 2 Questions:

1. A compass

Part 3 Questions:

1. The loop of wire - looping the wire concentrates the magnetic field into one area.

Time: 90 minutes

Electromagnet Lab

Purpose: To explore what affects the strength of an electromagnet.

Materials: Batteries, wire, iron nails, small paperclips

This is a student designed lab, so they may decide on different materials, but the list given would be adequate to do this lab. Having magnet wire will be best as it can withstand the heat better than other wire. It takes many turns to get a strong magnet, so if students are not seeing an effect, suggest many more turns. A rubric is attached.

Time: 45-60 minutes.

Magnetism Worksheet

Key

1 Answers may vary of course but some examples are:

- Magnets have two poles - observations of two magnets changing from attract to repel when one is flipped.

- Some materials may be induced to become magnets - observations of some objects that are not themselves magnets attracted to the magnets.

- Magnetic fields form loops from north to south - observations from iron filings

- Magnetic fields are stronger at the poles - observation of iron filings clumping more at the poles.

2.

3. As the magnetic fields between the wires are in the opposite direction, the two wires would be attracted to one another.

4. Object A - an uncharged non magnetic material

Object B - negatively charged object

Object C - Magnet

Object D - magnetic material

5. Magnetic field points down, force on the top is left, force on the bottom is right.

Electric motor construction

Purpose: Building a simple electric motor can be a rather daunting task. Viewing the linked video may help. Modify the procedure based on materials available.

1. The current goes through the coil, the coil produces a magnetic field, the magnet’s magnetic field puts a force on the coil’s field causing rotation.

2. It shuts off the current and shrinks the magnetic field of the coil. Without this, south poles would attract north poles as the coil until they were as close as possible and then they would stop rotating.

3. Having the center of mass of the coil near the line formed by the tails, magnet strength, amount of current.

4. To exert a force on the magnetic field produced by the coil.

5. No. The insulation stops the current from flowing. No current, no magnetic field in the coil, no force applied to the coil to cause rotation.

6. It would be like current going through a wire alone. The magnetic field would be much weaker.

7. Magnet strength, number of loops in the coil, distance between coil and magnet.

Time: 60 minutes

Fictional Physics - Hover Shoes

Project Rubric

Purpose: For students to be able to make an argument based on what they have learned for why hover shoes would not work.

This activity could be done completely out of class if you would like, or you could go through the introduction together as a class and then give the students time to work on outlining their paper in class. The final product is a 1-2 page paper. The rubric is given and should be given to the students before they write their paper.

Time: 60 minutes