012-03175E Instruction Manual and 3/93 Experiment Guide for the PASCO scientific Model ES-9054B ELECTROMETER FUNCTION B1 B2 D 3 C 10 V O 30 L T 100 S Model ES-9054B ELECTROMETER ZERO ADJUST scientific POWER OFF ON OUTPUT GND INPUT PUSH ZERO TO LOCK ZERO © 1987 PASCO scientific $7.50 012-03175E Electrometer Table of Contents Section Page Copyright and Warranty..................................................................................ii Equipment Return ...........................................................................................ii Introduction ..................................................................................................... 1 Operation ......................................................................................................... 1 Setup .......................................................................................................... 2 Measuring Charge ..................................................................................... 3 Measuring Voltage .................................................................................... 4 Measuring Current .................................................................................... 4 Using a Projection Meter .......................................................................... 5 Maintenace ...................................................................................................... 5 Battery Installation.................................................................................... 6 MOS-FET Replacement ............................................................................ 6 Schematic ........................................................................................................ 7 Parts List.......................................................................................................... 8 Technical Support ............................................................... Inside Back Cover i Electrometer 012-03175E Copyright, Warranty, and Equipment Return Please—Feel free to duplicate this manual subject to the copyright restrictions below. Copyright Notice Equipment Return The PASCO scientific 012-0xxxy Model Name manual Should the product have to be returned to PASCO is copyrighted and all rights reserved. However, scientific for any reason, notify PASCO scientific by permission is granted to non-profit educational institu- letter, phone, or fax BEFORE returning the product. tions for reproduction of any part of the manual Upon notification, the return authorization and ship- providing the reproductions are used only for their ping instructions will be promptly issued. laboratories and are not sold for profit. Reproduction under any other circumstances, without the written ä NOTE: NO EQUIPMENT WILL BE consent of PASCO scientific, is prohibited. ACCEPTED FOR RETURN WITHOUT AN AUTHORIZATION FROM PASCO. Limited Warranty When returning equipment for repair, the units must be PASCO scientific warrants the product to be free from packed properly. Carriers will not accept responsibility defects in materials and workmanship for a period of for damage caused by improper packing. To be certain one year from the date of shipment to the customer. the unit will not be damaged in shipment, observe the PASCO will repair or replace at its option any part of following rules: the product which is deemed to be defective in material or workmanship. The warranty does not cover damage ➀ The packing carton must be strong enough for the to the product caused by abuse or improper use. item shipped. Determination of whether a product failure is the result of a manufacturing defect or improper use by the ➁ Make certain there are at least two inches of pack- customer shall be made solely by PASCO scientific. ing material between any point on the apparatus and Responsibility for the return of equipment for warranty the inside walls of the carton. repair belongs to the customer. Equipment must be ➂ Make certain that the packing material cannot shift properly packed to prevent damage and shipped in the box or become compressed, allowing the postage or freight prepaid. (Damage caused by im- instrument come in contact with the packing carton. proper packing of the equipment for return shipment will not be covered by the warranty.) Shipping costs Address: PASCO scientific for returning the equipment after repair will be paid by 10101 Foothills Blvd. PASCO scientific. Roseville, CA 95747-7100 Phone: (916) 786-3800 FAX: (916) 786-3292 email: [email protected] web: www.pasco.com ii 012-03175E Introduction The Model ES-9054B Electrometer is an infinite With these features, you’ll find that your electrostatics impedance (1014 ý) voltmeter that can be used for demonstrations and labs are easier to perform and, with direct measurements of voltage, and indirect measure- quantitative data, are more informative as well. ments of current and charge. Because of its high The electrometer is battery powered by two 9 volt impedance, it is especially suited for measuring charge batteries, and comes complete with the batteries and a in electrostatic experiments. It has a sensitivity nearly shielded test lead. Instructions for inserting the 1,000 times that of a standard, gold-leaf electroscope, batteries are at the end of this manual. it has a center-zero meter that directly indicates charge polarity, and it measures charges as low as 10-11 coulombs. Operation The controls on the front panel of the electrometer are äIMPORTANT: explained in Figure 1. Whether you’re using the ① electrometer to measure voltage, current, or charge, the Never use the Electrometer for measuring following procedure should be followed each time you potentials in excess of 100 volts. turn on the electrometer. More information on making ② Never connect the electrometer to an electro- accurate measurements is given in the sections that follow. static generator such as a Van de Graff generator or a Wimshurst machine. ③ Never touch the input leads until you have grounded yourself to an earth ground. A person walking across a rug on a cool, dry day can easily pick up a potential of several thousand volts. 1 012-03175E Mechanical zero adjust screw (adjust with power off) Select voltage range (3, 10, 30, or 100 FUNCTION volts full scale) or B1 B2 D 3 C test batteries 10 V (B1 and B2) O 30 L T 100 S Model ES-9054B ELECTROMETER ZERO ADJUST scientific POWER Zero meter (zero OFF ON switch should be in OUTPUT GND INPUT PUSH ZERO TO LOCK ZERO LOCK position) ZERO Zero Switch: In PUSH TO ZERO 0-3.6 volts for driving setting, pushing knob will a projection meter discharge the electrometer Connect test lead here Connect to earth ground Figure 1 Front Panel Controls Setup ① Before turning on the electrometer, check that the charge or voltage. Set the FUNCTION switch to the meter reads zero. If not, turn the Mechanical Zero desired voltage range. The range setting refers to the Adjust screw, located just below the meter face, un- voltage input required to produce a full-scale meter til it does. deflection (e.g., a setting of 30 means that a full scale ② Slide the POWER switch to the ON position. meter deflection indicates a voltage of 30 volts). ③ Check the batteries: a. Turn the FUNCTION switch to B1. The meter pointer should read to the left of the B1 line at the bottom of the meter face. If the pointer falls ä Important Points for General Operation: within the area labeled B1, see the battery re- ① Between measurements, always press the Zero placement section at the end of this manual. Switch to discharge all current from the electrom- b. Turn the FUNCTION switch to B2. The meter eter. (The Zero Switch must be in the PUSH TO pointer should read to the right of the B2 line at ZERO setting.) Shorting the test leads together is the bottom of the meter face. If the pointer falls insufficient. There may still be stray charges within the area labeled B2, see the battery re- within the electrometer circuitry. placement section at the end of this manual. ② When adjusting the zero point of the electrom- ④ Zero the meter: eter, always turn the Zero Switch to the ZERO a. Turn the FUNCTION switch to 3. LOCK position. ③ b. Turn the Zero Switch to the ZERO LOCK set- For good results, it is essential that the elec- ting. trometer be connected to an earth ground (a water pipe or the ground wire from a 120 VAC socket). c. Adjust the ZERO ADJUST knob so the meter Only an earth ground provides a sufficient drain reads zero volts. for excess charges that may build up during an ⑤ Turn the Zero Switch to the PUSH TO ZERO set- experiment. It is also helpful if the experimenter is ting. grounded. Just touch one hand to a good earth ⑥ Connect the test lead to the INPUT connector of the ground while, or just before, making measurements. electrometer. ⑦ Connect the GND post of the electrometer to an earth ground. You’re now ready to use the electrometer to measure 2 012-03175E Measuring Charge Measuring Charge by Induction Charge measurement with the electrometer is indirect, Under most conditions, the best way to measure charge but simple. It is based on the relationship Q = CV, is by induction, using a proof plane and a Faraday ice where pail such as those included with PASCO’s Demonstra- Q and V are the charge and voltage across a capacitor tion Electrostatics System. The proof plane is simply a and C is the capacitance. The electrometer can be small conductive disk on an insulating handle. You thought of as an infinite impedance voltmeter in can make your own ice pail