Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . Fig. 113.—Weston milliamperemeter. At this point the writer may be permitted to digress for a momentfrom the subject proper and call to the mind of the reader the funda-mental nomenclature governing electrical measurements—as far asit is utilized in the following discussion. By the term ampere is 206 DISEASES OF THE DENTAL PULP meant the unit of strength of a current. A milliampere ispart of an ampere, expressed as A volt is the measurthe unit of pressure of the current, I e., th
Diseases of the soft structures of the teeth and their treatment; a text-book for students and practitioners . Fig. 113.—Weston milliamperemeter. At this point the writer may be permitted to digress for a momentfrom the subject proper and call to the mind of the reader the funda-mental nomenclature governing electrical measurements—as far asit is utilized in the following discussion. By the term ampere is 206 DISEASES OF THE DENTAL PULP meant the unit of strength of a current. A milliampere ispart of an ampere, expressed as A volt is the measurthe unit of pressure of the current, I e., the electric power necessarpto drive a current of 1 ampere through a resistance of 1 ohm. It isreferred to as the electro-motive force and expressed as ohm measures the resistance of a circuit through which a currentflows and a watt represents the units of power. The currentstrength flowing in a circuit is equal to the pressure divided by the. 1 ,,.. nt. Switchboard for electro-sterilisation. (Mcintosh.) resistance. The resistance equals the pressure dividedstrength. The pressure equals the strength multiplied bysistance. Therefore, in simple term-:Ampere volts * ohms. Ohms = volts + amperes. = amperes X volts X amperes. lunation as related to the process of by thethe re- VoltsWatts [•(•III tin- Kt\ c r\]»l iterilization, it is obvious that the correct measurement electro-of the NECROSIS AND GANGRENE OF THE DENTAL PULP 207 amount of current applied to a patient is of the utmost importance,as it is the safest means of guiding us during its application. Hencethe importance of procuring a trustworthy best instruments are those constructed after the Deprez-dArsonval deadbeat (non-trembling) type. The Weston milli-amperemeter (Fig. 113) is a most reliable current gauge. Theface of the latter instruments, suitable for this work, should becalibrated in 5 milliamperes, with subdivisions of yV to ^V
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