In the articles of digital multi meter I have seen that the authors only discuss the digital volt meter and they dont write any thing about the opperation of digital ammeter.What is the reason for that ?
also if someone of you have a online link about the operation of digital ammeter, and digital ohmmeter please reply me
if any one have some links about operation of digital frequency meter,digital power factor meter, digital LCR bridge and such type digital instruments plese reply me

 

If the digital meter is a "multimeter", then an ammeter function is built in.

Using those meter types as search terms in Google brings up informative links - http://en.wikipedia.org/wiki/Ammeter

 

In the average multimeter there is a low ohm resistor (often just a piece of wire) and the multimeter measures the voltage across that and converts it to a current. I think that the resistance meter sends a small fixed current through the test resistance, measures the voltage and converts it to a resistance for you.