Search results
Results from the WOW.Com Content Network
The moving iron ammeter symbol is in the lower-left corner of the meter face. Moving iron ammeters use a piece of iron which moves when acted upon by the electromagnetic force of a fixed coil of wire. The moving-iron meter was invented by Austrian engineer Friedrich Drexler in 1884. [5]
A moving coil galvanometer can be used as a voltmeter by inserting a resistor in series with the instrument. The galvanometer has a coil of fine wire suspended in a strong magnetic field. When an electric current is applied, the interaction of the magnetic field of the coil and of the stationary magnet creates a torque, tending to make the coil ...
This moving coil galvanometer is mainly used to measure very feeble or low currents of order 10 −9 A. To linearise the magnetic field across the coil throughout the galvanometer's range of movement, the d'Arsonval design of a soft iron cylinder is placed inside the coil without touching it. This gives a consistent radial field, rather than a ...
An early D'Arsonval galvanometer showing magnet and rotating coil. A galvanometer is an electromechanical measuring instrument for electric current.Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
Moving coil instruments can respond only to the average value of the current through them. To measure alternating current, which changes up and down repeatedly, a rectifier is inserted in the circuit so that each negative half cycle is inverted; the result is a varying and nonzero DC voltage whose maximum value will be half the AC peak to peak ...
AVOmeter is a British trademark for a line of multimeters and electrical measuring instruments; the brand is now owned by the Megger Group Limited. The first Avometer was made by the Automatic Coil Winder and Electrical Equipment Co. in 1923, and measured direct voltage, direct current and resistance. [1]
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Normally the moving coil is suspended from a pivot above it, so the linear motion along the core causes the coil, and an attached pointer, to rotate over a dial. [5] The Weston frequency meter also uses tuned circuits, but in this case it is the relative inductance between two such circuits that creates the meter's movements.