One of Project BoxSand's goals is to close-the-loop on effective curriculum reform iterations. We are coding all the content and resources, every text, video, and homework question, to a set of atomistic learning objectives. As students go through the course we can see how their path through resources relates to successfully completing these learning objectives. This allows us to find the most effective resources for accomplishing the desired learning outcomes.  

Summary

All charged objects produce a thing we call their electric field. It is not observable in the conventional sense and might be thought of as a clever way to keep track of how charged objects interact. The field from one electron can influence another electron and the result is they feel a repelling force.

Atomistic Goals

Students will be able to...

1. Be able to interpret electric field diagrams

2. Be able to calculate the electric field for a point charge or a group of point charges

3. Be able to explain the Δr̂  unit vector and apply it mathamatically to problems

4. Be able to find the force of a charged particle in an electric field

5. Be able to roughly sketch or identify the field for simple charge distributions

6. Be able to explain the concept of a field and how it pertains to the electric field

7. Students should understand the concept of electric field, so they can:

    i. Define it in terms of the force on a test charge.
    ii. Describe and calculate the electric field of a single point charge.
    iii. Calculate the magnitude and direction of the electric field produced by two or more point charges.
    iv. Calculate the magnitude and direction of the force on a positive or negative charge placed in a specified field.
    v. Interpret an electric field diagram
    vi. Analyze the motion of a particle of specified charge and mass in a uniform electric field.
8. Students should understand the nature of electric fields in and around conductors, so they can:

    i. Explain the mechanics responsible for the absence of electric field inside a conductor, and know that all excess charge must reside on the surface of the conductor.
    ii. Explain why a conductor must be an equipotential, and apply this principle in analyzing what happens when conductors are connected by wires.
    iii. Show that all excess charge on a conductor must reside on its surface and that the field outside the conductor must be perpendicular to the surface
    iv. Describe and sketch a graph of the electric field and potential inside and outside a charged conducting sphere.

The success of this curriculum relies heavily on preparing for lecture by engaging with the pre-lecture study resources below. The pre-lecture videos and homework have the strongest correlation with success, followed by the reading. More engagement with all of the resources is correlated with better performance in the course. Students who do the pre-lecture study and homework also report much greater satisfaction with the course. Routine is the heavy lifter of success!

Reading

To prepare for the pre-lecture homework and the lecture material, read the following OpenStax textbook chapters, BoxSand introductions, or other linked articles.

Re-read the BoxSand introduction to the Electric Field. Pay close attention to the part about point charges and finding the net E-field

 

Read the OpenStax section 18.5 on Electric Field Lines: Multiple Charges

 

Videos

To prepare for the pre-lecture homework and lecture materials, watch the following required videos. Research shows that taking notes by hand is the preferable method for retention. For this reason these videos are paced so that you can write down everything we write down. There are also supplementary videos that are strongly suggested but could be viewed after lecture while working on practice problems. Watching all of these videos is shown to be one of the strongest correlators with success in this course. 

| Required Pre-lecture Videos |

net E field - vector addition(5min)

net E field - vector addition(5min)

non-uniform E-field - conceptual point q(7min)

non-uniform E-field - conceptual point q(7min)

E-field from point charge - algorithm calculation with rHat(11min)

E-field from point charge - algorithm calculation with rHat(11min)

E-field from point charge - example(13min)

E-field from point charge - example(13min)

| Supplemental but Suggested |

E-field from point charge - simple symbolic example(6min) **

E-field from point charge - simple symbolic example(6min)

   

Simulations

 

 

Other Suggested Resources

    1. none

 

Pre-lecture Homework

Complete the following assignment before attending lecture or answering the lecture questions. Watching the videos and performing the suggested reading before attempting these questions will likely be necessary.

    Pre-lecture Homework | Calendar

 

In order to maximize efficiency while learning physics, education research has suggested a Flipped Classroom approach with multiple Guided Peer Learning (GPL) lectures a week. To get the most out of these events students need to front load the lecture with pre-lecture study, outlined above. Attending a live lecture is highly preferred but if you're unable to, there is an asynchronous alternative. During lecture it is important to either use a digital version with a tablet and pen, or print a copy to write on. If the live lectures feel too fast, read through each lecture question and prepare before class begins. Many questions will be skipped due to time constraints, it is a good study strategy to come back and try to answer those questions.

 

Lecture Templates

The blank template workbook is provided so that you do not have to write down the questions or redraw complicated figures.

    Lecture Template | Calendar

Lecture Solutions

The completed templates will be available within one week of the last lecture class. It is an important metacognative step to review the questions you've answered that we were unable to cover in class.

    Lecture Solutions | Calendar

The most important post-lecture activity is doing your post-lecture homework shortly after completing the lecture questions. You learn physics by practicing problems! Occasionally there may be additional resources on the BoxSand site that we feel could be helpful in your learning. Those resources will be linked here.

 

Reading

    1. none

Videos

    1. none

Simulations

    1. none

Other Suggested Resources

    1. none

Example Problems and Practice

(1) What is the magnitude of the Electric field at a location $r = 2 \hspace{0.2 cm} nm$ from a point charge with charge $q=10 \hspace{0.2 cm}nC$ that is located at the origin?

 

(2) Three point charges $q_1 = q_2 = q_3 = 5 \hspace{0.2 cm}nC$ are placed equidistant from each other on the x-axis: $q_1$ is located at $x= -2 \hspace{0.2 cm}nm$, $q_2$ is located at the origin, and $q_3$ is located at $x = 2 \hspace{0.2 cm} nm$. A point charge $q_4 = 1\hspace{0.2 cm} nC$ is placed on the y-axis, 2 namometers up from the origin. (a) What is the magnitude of the electric force that $q_4$ feels? (b) What is the direction of the electric force on $q_4$? (c) What is the direction of the electric force if $q_4 = -1 \hspace{0.2 cm}nC$ instead?

 

Post-lecture Homework

Complete the post-lecture homework assignment as soon as possible after completing the lecture questions. If you need help, and you've already watched the pre-lecture videos and read the pre-lecture readings, reach out to one of our many support systems available here: support site.

    Post-lecture Homework | Calendar

One of the main learning objectives is improving problem solving and critical thinking skills. These are high on Bloom's Taxonomy of thinking and require synthesizing multiple logical ideas and concepts into a consistent framework. To improve these skills requires continually pushing the envelope on what you can analyze. Challenge homework is designed to push you, often to the point of reaching out for help. Luckily we are ready to support you with our live and asynchronous support. The last objective of challenge homework is for you to write out your solutions clearly, have them graded by a human, and partial credit given. Exams are all about partial credit and a clearly organized solution that leads the reader through the logical pieces. Challenge homework is place to practice these steps. For more help on any studies or homework, see our support site.

Your challenge homework solutions are to be saved as a PDF and uploaded to Gradescope.

Challenge Homework Questions

Download the questions below and either answer them digitally with your tablet and pen or by hand.

    Challenge Homework Questions can be found on the calendar.

Challenge Homework Solutions

Challenge homework solutions will be available within one week of their due date.

   Challenge Homework Solutions | Calendar