# Wright State University Lake Campus/2016-9/Phy2410/log

### 29-Aug

Went through syllabus. Did echo-string quiz in lab.

Your account will span Wikiversity, Wikipedia, Commons, and Wikibooks

1. No username can be anonymous on this campus. Your classmates will likely discover your identity. One option is to quasi-violate Wikimedia policy and have a "public" username, and different private one.
2. You are advised not to worry about previous consideration and pick a "permanent" username that you might use for the rest of your life. Pick an unembarassing username that not too long, avoid spaces and other odd symbols.
1. Use one you already know
2. Use one that you might forget, but give me the password. (Never give your "important" passwords to anybody; but keep in mind that very little harm is done if you give me your password

### 5-Sep

Express electric field due to point charge

### 12-Sep Lab: Surface integrals in polar coordinates

• Importance of labeling dummy variabls as such: ${\displaystyle \int _{0}^{x}xdx}$ is confusing, instead change variables, or use a tilde:

${\displaystyle \int _{0}^{x}{\tilde {x}}d{\tilde {x}}=\int _{0}^{x}sds={\frac {1}{2}}x^{2}}$

### 26-Sep

1. Extend area of "washer" integral to the volume of thin shell of inner and outer radii of a, b, respectively. Let
${\displaystyle R={\frac {a+b}{2}}\qquad T=b-a}$

#### Lab

Make a diagram that explains dA in polar coordinates.

### 3-Oct Definition Worksheet, Term paper, T1 fix

#### Worksheet

You may collaborate with classmates

Answer each of these questions in the space below. Use the internet to obtain two sources. One can be Wikipedia and the other can be Physics equations, but if you use both, you need a third link. In each case, indicate the symbol(s) commonly used to define the entity, as well as one or more units that are used.
1. Define the electric field in terms of charge and force.
2. Define the Coulomb in terms of the charge of an electron.
3. Define the Coulomb in terms of the force between identical charges.
4. Define the Volt in terms of the work required to move a charged particle from point A to point B.
5. State at least one relationship between electric field and voltage difference (there actually are three relationships if you look at it a certain way).
6. Calculate the line integral ${\displaystyle \int {\vec {g}}\cdot {\text{d}}{\vec {\ell }}}$ from the origin to the point (x,y)=(4,3), where (in SI units)${\displaystyle {\vec {g}}\approx -10{\hat {y}}}$ (m/s2). What are the units of this integral?
7. Define the capacitance in terms of stored charge and voltage between two points. Do not use the value of a capacitance of a parallel plate capacitor.
8. Look up the capaicatance of a typical coaxial cable, and make an electric field diagram describing this geometry. Find and sketch at least one other geometry for a capacitor that is not a parallel plate capacitor.

#### Term paper

• One option is to write test questions based on this. This test will be closed book.
• Another option is to make a simple mass/spring demonstration and make a Youtube video of it.

#### Test 1 fix

Correct me before this weekend if this information is incorrect:

On Version 1 the correct answer is d on question 13
On Version 2, the correct answers are:
e on question 6
c on question 11

See Pilot (Content) for the answer key that I used.

### 24-Oct

Starting with two pages, On upper left corner write: last, first, phy2410 161025. Upper right corner has page number.

Or google: phet circuit construction kit dc

#### Multiple choice quiz on definitions

Give a right or a right and wrong answer to each of the following.

1. Define the electric field in terms of charge and force.
2. Define the Coulomb in terms of the charge of an electron.
3. Define the Coulomb in terms of the force between identical charges.
4. Define the Volt in terms of the work required to move a charged particle from point A to point B.
5. If mgh is potential energy and m is analogous to mass, what is analogous to electric field?
6. If mgh is potential energy and m is analogous to mass, what is analogous to voltage?

#### Test Kirchoff's loop law on a simple circuit

Draw the circuit in the handout. Change one voltage and three resistances.

1. Verify Kirchoff's loop law for loops 1 and 2, using your non-contact ammeter to measure the current. Keep in mind that the moving circles are electrons, so that current is going the opposite way.
2. Verify Kirchoff's node law for one of the nodes.
3. Misuse your internal ammeter to find the current through a resistor. Why did this happen?
4. Now mis-measure the current through the battery. What went wrong?

### 31-Oct

#### HW due Thursday

• Homework due BEFORE lab on Thursday: Complete the SCR lab on page 22 of "Discover Electronics" of Mr. Circuit 1.

#### Optics definitions

1. Review definitions
1. Object point is the point from which which rays diverge before they strike the lens
2. If the rays actually cross after leaving the lens, it is a "real" image. (Real images can be used to burn something with the sun's rays).
3. If the rays diverge from a point but are never physically at that point, it is a "virtual" image (a flat mirror makes virtual images).
4. Optical axis is the line "normal" (i.e. perpendicular) to the optical center of the lens (if the lens is symmetric, the optical center is the center).
5. All rays parallel to the optical axis meet at the one of the focal points of a "converging" lens.
6. All rays parallel to the optical axis diverge from a focal point of a "diverging" lens.
7. The focal length of a lens is the distance from the focal point to the lens. If the lens is thin, both focal lengths are the same.
8. Rays striking the optical center of a thin lens are (almost) undeflected.
9. There are three "easy" rays associated each object point of a lens.
10. A simple formula relates image and object distances: 1/p + 1/q = 1/f, where the object/image distances p,q are positive and f is positive for a real image situated to the right of the lens that was formed by an object to the left of the focal point.
2. In-class activities:
1. Make hand-drawn sketches of images for a converging lens if p = f/2, f, 2f, and 3f.
2. Repeat the above, but for a diverging lens.
3. Make a sketch showing how a far-sighted person can move the image of small print in a book to infinity using reading glasses.
4. Make a sketch showing how a near-sighted person can move the image of a distant object close the the eye using corrective glasses.

### 7-Nov The RC circuit

Hand in to dropbox if at all possible. You have a wide choice of options on the format. If it looks like you did sufficient effort, you will get 85%. Grades higher than that are not so easy to achieve because they will be judged by utility for this course. Here are some ideas:

1. Scan one document on campus to a pdf and use your H-drive to drop it into the dropbox. This verifies that next year we can have reports all paperless. A scanner at the front of Room 196 cannot be used if someone is teaching. But there are two scanners each in the backs of Rooms 183 and 185 that you can quietly use even if a class is in session (if no student is using it).
2. Multiple choice question for future classes.
3. Explanation or solution to a problem or question already in the bank.
4. An essay that (1) supports the concept of open source teaching and (2) offers ideas for improving this course. You may post essays (anonymous or not)on Wright State University Lake Campus that oppose the concept, but they will not count for (or against) your grade.

Click w:Permanent Link left sidebar under Tools. The url links to the history of a page. Example:

https://en.wikiversity.org/w/index.php?title=Wright_State_University_Lake_Campus/2016-9/Phy2410/log&oldid=1631304


sss

### 21-Nov

Next lab homework due at 840 am. Tuesday. Transister Oscillator page 28.

0.1% penalty for not doing circuit homework this time.

### 28-Nov

Due next week on day of the test TEST before 2 pm is page 30 circuit with the 555 timer.