Wright State University Lake Campus/2017-9/Phy2410/log
- 1 Office hours and calendar links
- 2 T 29 August 2017 (UTC)
- 3 R 31 August T1 study guide
- 4 T 5 September 2017 Find E from 2 point sources
- 5 Th 7 September 2017 Line integral to find E field (also Tue 12 Sep)
- 6 T 12 Sep
- 7 Before T1: shorter equation sheet
- 8 Thurssday 21 September Lab (get here by googling Wikiversity and start without me)
- 9 Tues 26 September-Just like Thursdaʏ
- 10 Thur 28 sept
- 11 prep for T3 24 October
- 12 Thurs 26 October Magnetic fields, cross product and right hand rules
- 13 nexθ
- 14 scrapbook
|Before Test 3|
T 29 August 2017 (UTC)
Sorry! I lectured from last year's study guide. The echo and sound wave questions are not on this exam. Use the new study guide.
Lecture: Study guide. Attendance policy.
Lab: Mr Circuit inventory
Do not come on Tuesday unless you are in that section. But if you are in the Tuesday section you are more than welcome to switch to Thursday. We will discuss attendance and how lab reports will be done. First lab: Inventory Mr. Circuit and
R 31 August T1 study guide
Lab: Mr Circuit inventory
Lab: Mr Circuit inventory
T 5 September 2017 Find E from 2 point sources
Lecture: Defined electric field, field point, source point, coulomb, amp. Did coulomb's law for first quiz (find E). Discussed the vector addition problem, using the unit vector as the r vector divided by its amplitude. Showed them the hard problem (dipole) but did not solve in class/
Work in groups of five or less and to the sparkfun website and find a topic, explain it, and pose a multiple choice question on it. All reports must be handed in on paper, but a permalink to your WV userpage is good enough. I can find you a place to write if you have no place on Wikiversity. As an alternative you can also do the hydraulic analogy to current, voltage, resistor, node and/or capacitor.
Th 7 September 2017 Line integral to find E field (also Tue 12 Sep)
Analyse a breadboard circuit found on commons:main page
How not to abuse a voltmeter
Simple answer: Only measure voltage!
Make it possible for a person to read your report and know what you did: We constructed this circuit after looking at a photograph depicting a breadboard connected to four 1.5 volt batteries.
T 12 Sep
Does your home computer easily read the links to the textbook using the Table of Contents on your PDF browser?
Planned Lecture: Equations#19-Electric_Potential_and_Electric_Field F=qE ... E=kq/r2 ... ΔV=Edcosθ, where F is force (Newtons), q is charge (Coulombs), V is "Electric Potential" (or simply "Volts"), r is distance. Note this gives you two equivalent units for E: N/C (newtons/coulomb) and V/m (volts/meter). The only other thing you need to know by heart is that 1 A = 1 C/s (amp is a coulomb per second, or the rate at which charge flows through a wire).
Later we do the capacity of an object to store charge at a given voltage: Q=CV, where C is the capacitance. A large parallel plate capacitor has a large area with the plates close together (which keeps the voltage down).
Before T1: shorter equation sheet
See File:Guy vandegrift pdf.pdf, which is best read online by clicking "original file" or going straight to it at https://upload.wikimedia.org/wikiversity/en/d/d5/Guy_vandegrift_pdf.pdf
Thurssday 21 September Lab (get here by googling Wikiversity and start without me)
Do A6 (How a diode works) on page 20-21, and note how this "one-way" street works differently in each direction.
Here, you will try to understand in more depth why the diode fails to operate when "backwards". Do this by measuring the voltage at each point (with respect to the negative side of the battery which we shall call "ground" (zero volts).
Do A7 (SCR) and note how it acts as an electronically activated switch
I don't even know what is going on here. We will find out.
I will quickly demo A5 for all of you (the loudspeaker)
Tues 26 September-Just like Thursdaʏ
Thur 28 sept
Lecture: We covered all of Test 2 except the last two Gauss law problems and the power drift velocity quiz.
Malus Law lab
Into: Malus's law predicts how much light comes out of a polarizing filter if the incident light is already polarized.
Procedure: Carefully draw an equilatoral triangle and bisect it with a perpendicular to a midpoint. Divide the long side into 10 parts by first cutting it in half, and making a 2/3 split before cutting it into five equal pieces. Estimate the height of the triangle.
Lab kit A8 page 24 npn transistor.
Tues 17 Oct
How many Thursday Lab people say "yes" to these three quesitions:
prep for T3 24 October
- Test 3 is Thursday November 16, 2017
The first listed quiz is a repeat of line integrals. Only one out of 13 questions will be on this quiz.
Thurs 26 October Magnetic fields, cross product and right hand rules
Lab:Nine volt batteries in series
Wikipedia gives the following values for the total body impedance of a hand to hand circuit for dry skin, large contact areas, 50 Hz AC currents (the columns contain the distribution of the impedance in the population percentile; for example at 100 V 50% of the population had an impedance of 1875Ω or less):
|25 V||1,750 Ω||3,250 Ω||6,100 Ω|
|100 V||1,200 Ω||1,875 Ω||3,200 Ω|
|220 V||1,000 Ω||1,350 Ω||2,125 Ω|
|1000 V||700 Ω||1,050 Ω||1,500 Ω|
- See first wikipedia:Electric Shock, but keep in mind that this is one topic where Wikipedia should not be trusted (it's probably correct but the consequences of being wrong can be grave.)
- NIH review article by Fish and Geddes pdf
- Articles by Dalzeil: Electric shock hazard .. [preprint (on voltages) .. Let go currents and voltages. Bernstein: Electrical Shock ... Standards
- See also my collection from scholarly articles:
One 9V battery with a 10W 20-Ohm resistor. Measured voltage was 7.42 volts. Open terminal voltage was 9.26V. Internal resistance is 5.1 ohms.
Repeat with same resistor different battery: 7.27 and 8.2 volts: Internal resistance is 2.6 ohms.
- intro to gauss law: https://www.youtube.com/watch?v=q78oByOGdjk
- Counting field lines: https://www.colorado.edu/physics/phys1120/phys1120_sm11/lecture-notes/CH21.pdf
|hide the mess|
By 4:45: Have your Mr. Circuit board.
Either volunteer or nomoninate a report that is better than yours to share with the class.
Put your name on postit notes I will provide.
- http://www.wright.edu/~guy.vandegrift/wikifiles/Electric%20Shock%20Hazard%20Dalziel.pdf Page 42