This looks like a complex and physically dangerous area. Some of the efforts will be simply rubbing together things which make small amounts of static electricity (see triboelectric).
Guidance from the involved units:
N | = | Force, 'Coulombic force'. Output from Coulomb's eqn |
N/C | = | Electric Field (strength), 'E field', 'E'; (= V/m), spatial density |
V | = | Voltage, 'potential' = J/C = N•m/C; 1/r calc; (Energy per C) |
J | = | PE: W=VQ, total PE of charges in Q (XAM p78.7) |
1. draw E fields | calculate and display E field vectors or contours, Win10, py |
2. emit negative ions | actually make electrons in a non-vacuum environment. |
3. voltage multiplier | CCW, "Cockcroft-Walton" voltage multiplier (section below). |
4. electrometer | Measure the strength of weak E-fields. Try using oscilloscope too. |
5. make capacitators | get the hang of plate separation, dielectrics etc. |
6. measure emitters | with Junior Theremins. Record events on video. |
Interactions with magnetic fields will be handled by the magnetics prjt or one of its component projects.
Links and vocab will collect here, at least temporarily. Most will migrate to glossary_sci.html (aka 'gsci').
See section on 'atmospherics' below.
The real code file is edited in python IDE. It proved risky to have 2 editors active. files 'review*.txt' are displayed in sep windows, side by side. advice: when saving interesting results, merge review files and rename w/ 8 digit date.
eFields.tws | p/eFields/ | reviewCode.txt,define_,todo_,html files |
_eFields.tws | Python34/examples/ | reviewOuts.txt, (fieldDraw.py if no py IDE running)
edits copies of eFields.tws files. for L-R code moves |
_fieldAssist.tws | Python34/examples/ | bounce1.py, _unitNotes.txt, gsci, bounce
function() snippets (docdoc.txt) |
_field.tws | Python34/examples/ | temporary. don't expect this to exist long...
helpful py files (bounce, graf, egList...) |
Be sure to understand this electric_field, gsci Notes on the program's devt.: # the grid is optionally computed and drawn. The only reason not to # draw it is to see the charges' acceleration and velocity vectors - # which is not going into the 1st pass of this model (180725) gridScale, dist between points. gridDelX, DelY eFld[ ] x,y's for field arrow at this point grid[ ] [ ] has .x .y ?total length? Drawing ================================================= The Charges gets drawn as little circles, dif colors for +,- The field exactly at a charge is perpendicular to the page! The field drawing only makes sense at 'grid' points which don't match charge positions. Field is an arrow, arrowLen optimizations, improvements, damned ideas! ============== Any way to only (re)calc what needs calculating? yawn...
Does this make ozone? Would this draw particulates to a surface which could be cleaned easily. Would the plasma ball (globe) also do this?
physical mount: Talenti ice cream jars. 1 pint, 2 pint outer plate choices: 0.025" aluminum sheeting. ouch! expensive. Home Depot steel soup can split and wrapped around the 1 pint jar(s). 'wavey' aluminum foil, kitchen variety. wrapped several (4-5?) times. inner plate choices: 0.025" aluminum sheeting. coiled up. 3.25" or 2.75" wide 1/4" x ~4" long screw approximately centered in jar, held by top. "tube" was a 7/8" diameter x ~4" alum tube, centered in jar, held by top steel soup can used as inner plate on one of the 2pint jars. "small can" dielectrics air, distilled water, paraffin measurements made with my best VOM (Extech).'dielectric' in gsci
nF | jar num | jar size | outer sht | inner sht |
dielectric | comments |
---|---|---|---|---|---|---|
0.873 | 1 | 2 pint | foil only | small can | water | C slowly increased. 6.7x increase |
0.129 | 1 | 2 pint | foil only | small can | air | |
0.745 | 1 | 2 pint | foil only | screw | water | slowly increased to .755; 24.5x |
0.031 | 1 | 2 pint | foil only | screw | air | |
2 | 2 pint | alum | alum | paraffin | ||
0.618 | 2 | 2 pint | alum | alum | water | 2.78x increase over air |
0.222 | 2 | 2 pint | alum | alum | air | |
0.194 | 3 | pint | steel can | tube | water | 6.25x |
0.031 | 3 | pint | steel can | tube | air | |
0.274 | 4 | pint | alum | tube | water | 8x increase |
0.034 | 4 | pint | alum | tube | air | |
4 | pint | alum | screw | water | HAVE THE TOP NOW | |
4 | pint | alum | screw | air | HAVE THE TOP NOW | |
0.324 | 5 | pint | alum | alum | water | 1.74 increase |
0.186 | 5 | pint | alum | alum | air | |
..................................................................................... | ||||||
0.037 | 6 | pint | alum | screw | paraffin | paraffin still warm. value floated a bit |
Flat plate capacitor, 6" x 23 7/8" x 1/4" aluminum sheets. Extech VOM 0.608 nF held apart with 3 tie wraps, spread out, 1 layer as thick as 1 tie wrap. 0.316 nF 2 layers of same tie wraps. separation ~ 0.1" # used 6 ties, crossed in 4 places. 3.24x nF single sheets of paper both separation and (?) dielectric Cap equation, gsci gives "C = eR * e0 * Area / separation" (area of plates=='A') = 6"x23.875" = .153m * .609m = 0.093m² C = eR * e0 * A / (separation=='d_m') d_m = eR * (e0=8.854187¤-12 F/m) * (A=0.093m²) / (C=3.24e-9F) # eR is the dielectric constant, aka 'relative permittivity'. so treating as 1. d_m = (eR=1) * (e0=8.854¤-12 F/m) * (A=0.093m²) / (C=3.24e-9F) d_m = 2.54e-4 m; d_in = .00997" => piece of paper is 1/100" thick.wrong . 500shts=2" so paper is .004" / sheet # could correct by assuming eR = 0.4 # so d_m would be ~ 1.0e-4 and d_in ~ .004" # but (practical) dielectric constants need to be > 1 #paper dielectric == 2.3 ; do I have an eqn upside down? Off a digit? d_m = (eR=2.3) * (e0=8.854¤-12 F/m) * (A=0.093m²) / (C=3.24e-9F) d_m = 5.81e-4 m = .0227" # that's worse. ~44 shts per inch, not 250. 1/2.3 = .435 is just about the number need (ideally 0.4) Observations: Capacitance values are small! well less than 1 nF (nano-Farad) When 2 homemade caps wired in parallel, values summed so they act like caps. Grabbing outside with your hand added to measured capacitance value. Sliding the central 7/8" tube out most of its length only reduced C _some_ ! The jar w/ wavy steel sides was signif lower C than one w/ solid alum. I hoped to charge caps w/ battery then measure voltage w/ VOM. didnt work The paraffin reading, jar 6. Expected much higher. 0.037 is like air! 'paraffin' defines a wide range of hydrocarbons. Maybe my Safeway paraffin is weird. Actually, 'like air' is generous. The VOM measures 0.031 when the leads are not connected to anything (maybe it measured me b/c I was holding leads). When I used the VOM to measure the C for my body, the value kept climbing and pretty quickly at that. Was the VOM charging my body? Detectable result? Questions: May have to re-measure. My body should not be part of the measurement. Commercial caps cite a voltage value as well as capacitance. What would be the V for these? Shouldn't the water to air ratio for jar caps should be constant? (ratio of dielectrics...) Could I duplicate a 'jar cap' design and get close to the same answer? Why doesn't distilled water show a dielectric nearer to 80, as mentioned in wikip? My distilled is not pure (?). Got it from Sprouts store, near by. Is the C fm bigger jars 'worth it' ? (think not. none of these C's are really usable...) If I use one of these caps in a tuned circuit, does the resonant freq match values here? Why do C values drift upwards (a bit) during some of the measurements? possible follow-ons: take, add a row of photos of the jars etc. run function gen square wave thru 2n2222 and caps. observe w/ 'scope, VOM A/C try a mineral oil dielectric? add measurement column for hand touching outer sheet? Apply the capacitor eqn to the flat plate cap. Reasonable answer?
rimstarorg: I should be accessible thru youtube.com made 37uF electrolytic cap. alum foil, paper towels, homemade liquid on paper towels. distilled water + sodium bicarbonate, baking soda
Consider: E _IS_ _charge_ atmosphere ~30 miles thick, 300kV dif. = 10kV/mile = 2v/foot avg. from https://en.wikipedia.org/wiki/Atmospheric_electricity { The air above the surface of Earth is positively charged, while the Earth's surface charge is negative. Because the atmospheric electric field is negatively directed in fair weather, the convention is to refer to the potential gradient, which has the opposite sign and is about 100V/m at the surface. There is a weak conduction current of atmospheric ions moving in the atmospheric electric field, about 2 picoAmperes per square metre, and the air is weakly conductive due to the presence of these atmospheric ions. (2e¤-12amps * 6.24¤18chgs/Coulomb * 1Coulomb/amp-sec) = 12¤6 particles/sec/sqMeter } TreshaEdwards.shtml { 'directed inward'. => positive up high, neg at earth's surface (?) 'at surface 66 N/C to 150 N/C. 150 more real' 'intensity decreases w/ altitude' (gradient(?)) '120 V/m at surface','exponential increase in conductivity w/ altitude'. 'at 30km alt, field as low as 300 mV/m' 'thunderstormsfield, usually reversing polarity under cloud' 'max current, world-wide, occurs at 1900 UTC' } Atmos eFld { '100V/m near surface' 'polarity: drives + chg downwards' 'polution affects chg distribution' } why it doesn't shock you as is. what is lightning (incl numbers, speed, rate), how's it form. what about familiar static shock (numbers). relationship to humidity. VDG vandegraff generator. use, risk, numbers. corona discharge. means of measuring electroscope. meters wiki,Capacitor instructables, DIY-Capacitor hi voltage cap using lg pop bottle, water, alum foil as means of generating static charge.
safety. gloves, safety signs, VDG discharging, cat safety.
These are inexpensive kits, even available at Fry's. 180824. They respond to changes in the local electric field using 'capacitive coupling'. They 'go nuts'when a cell phone transmits!
A spark maker. Historically the 'spark' was used to accelerate charged particles in science research but there seems to be a lot of interest nowadays in just making huge (2inch) sparks. A Marx Generator requires a circuit upstream which can make high voltage, such as the CCW (Cockcroft-Walton voltage multiplier). hobby system described. (searched 'marx generator')
link | description |
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todo list | for this project |
YouTube | Step-by-Step Science 'Electric Field, An Explanation'. intro. |
YouTube | Step-by-Step Science 'Electric Field, Calculating the Magnitude and Direction of the Electric Field'. very clear. speaker sounds like Sal Khan. |