Volt-ohm meter

Volt-ohm meter (EVOM-G, World Precision Instruments, Sarasota, FL, USA) with corresponding chopstick electrodes. 

TEER can be measured using chopstick electrodes and an EVOM epithelial volt-ohm meter (World Precision Instruments, Sarasota, Florida, USA). Nevertheless, as endothelial monolayer resistance is usually far lower than the one of epithelial cultures such as MDCK, accurate quantitative measurements of endothelial monolayer resistance require typical instrument such as Endohm-24S chamber electrode and the epithelial volt-ohm meter EVOMTM (World Precision Instruments, Sarasota, Florida, USA). The disadvantage of this method is that the plates containing the cultures need to be removed from the thermostat for measurements and changes in temperature are known to have strong effects on TEER and can pose problems during the process of TEER measurements in cell culture vessels. 

A VOM (Volt-Ohm Meter) is necessary to check power supply voltages, circuit continuity, resistances, etc. Conven-... 

Voltage (or volt/ohm) meter for measuring voltage strength in the electrotaxis chamber. 

The easiest electrical properties to measure accurately are voltage and resistance. Thus, the primary application tool of electrical measurement is the common volt-ohm meter (VOM), either as an analogue device or as its digital counterpart, the digital volt-ohm meter (DVOM). 

Volt-ohm-milliammeter (VOM) A general purpose multirange test meter used to measure voltage, resistance, and current. 

The diac can be studied with the circuit of Fig. 21.6, but using the dashed-line wire and leaving out the transformer for a while. The voltmeter is attached across the diac. When the pot voltage reaches the diac s trigger level, about 6 volts, the meter will go to nearly zero. The capacitor will discharge through the 100 ohm resistor. 

Sensitivity is a ratio of the response of a measuring device (meter) to the magnitude of the measured quantity (volts, ohms, amperes, etc.). Voltage-measuring devices are rated in ohms per volt (i2 ). On any particular range, it is obtained by dividing the resistance of the instru-... 

The next thing to do is set the meter to measure volts (dc, of course), in the 15 volt range. In order to put the voltmeter in the "2nd" position of Fig. 4.2, it is disconnected, and then its black probe is clipped to the junction between the two resistors, possibly by sharing an alligator clip on the white wire (Fig. 3.3, page 32). Its red probe is attached to the top end of the 100 ohm resistor, possibly by sharing an alligator on a red clip lead. Thus the voltmeter is said to be "connected across" that resistor. 

If another voltmeter can be borrowed, set it as an ohmmeter, in order to measure the resistance of yours set as a voltmeter, red probe to black, and black to red. The voltmeter will be observed to be about 30K, as noted in the figure. On a Radio Shack meter (Catalog number 22-218), at the lower left corner of the white dial, the black letters read "2KQ/V," which means that for every volt on the scale, there are 2,000 ohms inside the meter. Since the 15 volt scale is used, the input resistance is 30,000 ohms. 

A schematic diagram for a simple pH meter is shown in Figure 5.13. It is nothing more than a conventional potentiometer circuit. The precision slide wire (PSW) is calibrated in units of pH rather than in volts or ohms. A stable power supply is used, which may be a battery or a regulated electronic supply. The reference voltage source may be an unsaturated standard cell or a zener diode electronic reference. 

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