Galvanometer sensitivity

Fig. 1.—The Polarographic Reduction of 0.01 M o-Glucose in 0.2 M Aqueous Lithium Chloride Solution, in the Temperature Range of 20 to 80°. (The curves were recorded from —1,0 V galvanometer sensitivity — 1 50.)...

Fig. 2.—The Dependence of Wave Heights of 0.2 M n-Glucose on the Reservoir Height, in 0.02 M Lithium Hydroxide. (The reservoir heights were 1, 46 2, 34.2 3, 24.4 and 4, 16.4 cm. The curves were recorded from —1.0 V galvanometer sensitivity - 1 10.)...

Fig. 7.—The Time-dependence of the Reaction of 10 mM DL-Glyceraldehyde with 60 mM o-Phenylenediamine in Water at 25°. [The samples taken (0.5 ml) were added to a 0.3 M isobutylamine buffer (9.5 ml) of pH 10.4, and were recorded after 1, 2 2, 10 3, 20 4, 40 and 5, 90 minutes, from 0.0 V saturated calomel electrode h = 50 cm galvanometer sensitivity = 1 15.]...

Calculate the index by dividing the wave height / of the filtrate test by the wave height d of the denaturation test and multiplsdng the quotient by 15, provided that both tests were performed at the same galvanometer sensitivity ... 

If it is desired to use the biamperometric method for detecting the end point, then the calomel electrode and also the silver rod (if used) must be removed and replaced by two platinum plates 1.25 cm x 1.25 cm. The potentiometer (or pH meter) used to measure the e.m.f. must also be removed, and one of the indicator electrodes is then joined to a sensitive galvanometer fitted with a variable shunt. The indicator circuit is completed through a potential divider... 

The main drawback of the galvanometer-spot follower system is that the sensitivity level of the line is defined ab initio and cannot be modified except by increasing or decreasing the number of thermoelements in the circuit. A more versatile, but more expensive, system is provided by the addition of a dc amplifier to a recording voltmeter. 

The detector in a spectrometer must produce a signal related to the intensity of the radiation falling on it. For instruments operating in the visible region a photovoltaic or barrier-layer cell is the simplest and cheapest available. Current produced when radiation falls on a layer of a semiconductor material, e.g. selenium, sandwiched between two metallic electrodes, is proportional to the power of the incident radiation and can be monitored by a galvanometer. Barrier layer cells are robust and are often used in portable instruments but they are not very sensitive and tend to be unstable during extended use. 

The sensitivity of instruments using low resistance circuits is determined primarily by the sensitivity of the galvanometer (Figure 4.5). Electrode systems that have a high resistance, e.g. glass electrodes, require a high impedance voltmeter, which converts the potential generated into current which can be amplified and measured. Such instruments are commonly known as pH meters but may be used for many potentiometric measurements other than pH. 

Galvonogroph. The photographic record of a sensitive galvanometer arranged so that the mirror deflects a beam of light onto a moving film or paper... 

The Boyd and Harkins reference might be considered the first careful calorimetric work taking into account the special problems of immersional calorimetry it was also the first such work in which surface areas could be assessed (the B.E.T. method) as a necessary auxiliary for putting values on a imit area basis temperatiue changes were measured with a 36-junction thermocouple and a White double potentiometer with a sensitive galvanometer. 

This vapor pressure can be deduced from kinetic theory and the rate of arrival of Cs atoms per square centimeter per second (3,4). This arrival rate. A, can be calculated from the measured value of the saturation positive ion current. Langmuir first showed that if the tungsten is hot enough every cesium atom that strikes the surface evaporates off as a positive ion of cesium. This saturated positive ion current, i.p, can be measured easily with a medium sensitive galvanometer when the collector is negative. It is related to A by the equation... 

Other proposals bave been made to measure the intensity of the sound by means of a microphone and sensitive galvanometer. In the opinion of Marshall (Ref 2) and of Perez Ara(Ref 3), the weak point in these methods is that there is no necessary connection betw the intensity of sound and the efficiency of the detonator. Refs. l)F.Martin, ChemZtg 37, 90(1913) 2)Marshall 2, (1917),532 3)P rez Ara( 1948), 124 Speeific or Normal Volume. See tinder Volume of Gases Evolved on Det nation(or Explosion)... 

Fig. 7. Continuous recording of the limiting current Oxidation of fAreo-l,2-diphc-nylethyleneglycol by periodate. Decrease in the periodic acid concentration with time. 1M Acetate buffer of pH 4.3, 5 x 10 5 M-KIO4, 5 x 10 8Af diol. Current recorded at 10.4 V (mercurous sulphate reference electrode) at 15° C. Figures on the abscissae give the time in minutes the galvanometer zero and the current before the addition of periodate and after addition at / = 0 are marked. Full scale sensitivity 0.8 [zA...

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