Ques. What is a "sensitive" galvanometer?
Ans. One which requires a very small current or pressure to produce a stated deflection.
It does not follow that a galvanometer which is sensitive for current measurement will also be sensitive for pressure measurement.
Fig. 506.--Bunnell simple detector galvanometer. It has middle clamps and scale divided into degrees.
Ques. Define the term "sensibility."
Ans. With reference to mirror reflecting galvanometers it may be defined in three ways. First, in megohms, the sensibility being the number of megohms through which one volt will produce a deflection of one millimeter with the scale at one meter distance. Second, in micro-volts, the sensibility being the number of micro-volts which applied directly to the terminals of the galvanometer will produce a deflection of one millimeter on a scale one meter from mirror. The sensibility is best stated in megohms for high resistance galvanometers and in micro-volts for low resistance galvanometers, and is frequently given both for galvanometers for intermediate resistance. Third, in micro-amperes, the sensibility being the number of micro-amperes that will give one millimeter deflection with scale at a distance of one meter.
Ques. Upon what does the sensibility depend?
Ans. 1, Upon the number of times the current circulates around the coil, 2, the distance of the needle from the coil, 3, the weight of the needle, 4, the current strength, and 5, the amount of friction produced by its movement.
