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Digital electrostatic meter(Electron Counter)
In our circle activity named Electronics Hobby Circle in Nagoya we made many electric apparatuses or devices for physics education such as detectors of infrared, stopwatches and so on together. I introduce an electrostatic meter or an electron counter devised by Mr.TANAKA Eiji.
(1) ELECTRIC CIRCUIT
(2) TREATMENTS
(a) Attach a probe made of a little beer can to the red terminal (I write how to make it in the latter part of the papers).
(b) Put on the power switch. It takes a few minutes to be stable.
(c) Adjust zero point pushing the reset button, after changing the sensitivity switch to H.
(d) Begin to measure.
we can measure electric charge by 0.1［nC］minimum units in the case of H. sensitivity,
and by 1.0［nC］minimum units in the case of L. sensitivity.
(3) HOW TO USE
(a) We can find the electric charge of a electrified body including the positive or negative sign.
If you draw a electrified body up to the probe, you can find the electric charge.
(b) Stick a straw with paper sack in the probe and pull it out and then restore it in the original sack.
When you pull out the straw , the paper sack will be electrified positively and the meter will show the charge such as +○○［nC］. When you restore it in the original sack,the meter show the charge 00［nC］. We can find that all electrification happen when positive and negative charge separate from each other. We can make sure of the conservation of electric charge.
(c) You make a parallel plate capacitor of copper plates and OHP sheet and then if you electrify it with a dry cell, you can measure the charge.
(d) measurement of electric field
As we measure the charge induced by line of electric force entering the probe of beer can originally, we can think that we measure the
electric field. Then we can measure electric field if we use various kinds of probe.
(e) photoelectric effect
If you put a zinc plate polished with sand paper on the probe and give out a ray of ultraviolet on the plate, you see the meter show
positive charge increase gradually. We can find photoelectric effect by this device.
(f) Edison effect
You turn on an incandescent lamp and cover it with aluminium foil.
When you touch the foil and the probe together, you see the meter show the charge become more negative gradually. We can find Edison effect by this device.
HOW TO MAKE A PROBE
Make a φ2mm hole in the center of the bottom of a beer can and fasten a φ2mm×8mm bolt and two nuts and then solder a banana chip as shown in the figure
This was devised by Mr.TANAKA Eiji.
He teaches physics in the school as follows.
Seto High School
8-1, Higashiyama-cho
Seto Aichi Prefecture, 489
Japan