Physics 1090: Fundamentals of the Physical Universe

Unit 6: Electricity and Magnetism
Due October 5, 2011
20 points

Part 1: HTML (0 points)

Just as I did last week, I encourage you to learn some more HTML.  This is for your own good, not for a grade.  Some day you will thank me for this.

Last week, you learned to make an HTML file that displays some text when viewed in a browser.  (Wheeeee!)  This week, I'd like you to learn how to use HTML commands.  This lesson includes the most powerful HTML feature, the link.  (This is sooooo cool.)

Read the second HTML tutorial. It is fairly short, but it contains a lot of information. Then:

1. Create an HTML file, like you did last week.
2. Put some text into it.  Organize the text into paragraphs, so that all text is within bracketing <p> and </p>
tags.
3. Include some special characters (“entities”) in your text.
4. Include a hyperlink (enclosed by bracketing <a> and </a> tags) in your file.  Make the hyperlink actually navigate to a document on the web.  Word the text of the link and any accompanying text so that a user knows what to expect when selecting the link.

Save the file and upload it using the “Assignments” tool in Sakai.

If you wish, you may submit your entire homework answer in your HTML file!  In fact, I encourage you to do that.  It will be good practice.

• Here is the gateway to my HTML tutorials.
• Here is the second tutorial in the series.

Part 2: Electricity and Magnetism (20 points)

Answer one, and only one, of the following questions.

These questions are for you to combine different ideas from the unit and apply them to situations not directly addressed in class or in the textbook.  Think about the situation, and about the physics that applies to it.  See me for help if you are stuck.

1. Static cling.

The rule for the electric force is that opposite charges attract and like charges repel.  An object with zero charge should then neither attract nor repel a charge.  Why, then, do charged objects actually attract uncharged objects?

2. Stairway story.

Tell the story of what you and your group did in trying to make the “stairway circuit.”  Who did what, and what was your reasoning between the different things you tried?

3. Electromagnetic forces.

The fourth activity in the unit, “Electromagnetism,” contained three parts showing relationships between electric currents and magnetic fields.  For each part (rectangular currrent loop, swinging wire, and magnet and coil), describe:

• What the magnet did or what happened to it,
• What the electric current did or what happened to it, and
• what this demonstrates about the interaction between currents and magnetic fields.

(The hand-cranked generator used the interplay between electric currents and magnetic fields as well, but it wasn’t so clear how the parts were arranged.  The point there was not to illustrate the relationship, but to emphasize the universality of the principle of conservation of energy.)

4. Prior knowledge of magnets.

Did you ever play with magnets as a child?  Tell about it.

• Did you ever play with electromagnets?
• What rules did you find about how permanent magnets work?
• Did you ever break a permanent magnet, accidentally or on purpose, between its north and south poles? How did the pieces behave magnetically?

Take your choice of these tasks.  Do not submit answers to more than one of them. Just choose one, and submit it.  Your answer should thoroughly address all points of the question. An adequate answer will be several paragraphs long.

You may submit your answer as an electronic file using the “Assignments” tool in Sakai if you wish.  I encourage you to make it an HTML file, to reinforce your new HTML skills.