the range of an ammeter indicates the maximum current which can be measured with the meter. current is the excess of these values will cause serious damage to the meter. if an ammeter range of 0-15 amp, it will measure any current flow which does not exceed 15 amperes, but a current greater than 15 amperes will damage the meter.  

while the meter scales may have a range of 0-15 ampers, it full range for proposes of measure meant will be from about 1 ampere to 14 amperes .when this meter scale indicates a current of 15 amperes, the actual current is much greater but the can only indicate its maximum range. for that reason, the useful maximum of any other meters is slightly less than the maximum range of meter scales. 

A current of 0.1 amperes on this meter scale would be very difficult to read since it would not cause the meter needle to moves far enough from 0 to obtain a definite reading. smaller current such as 0.001 amperes would not cause the meter needle to move and thus could not be measured at all with the meter. the useful minimum range of a meter is never extended down to zero but extends instead only to the point at which the reading can be distinguished from zero. 

The ammeter range is usually in multiples of 5 or 10 such as 0-5 meters, 0-50 amperes, etc. range above 0-100 amperes is not common since the current is in excess of 100 amperes is sold used. 

Demonstration-reading meter scales:- 

You have observed that the current ammeter range to use in measuring the current flow though the lamp is the 0-1 ampere range. to show the effect of parallax on the meter reading, the instructors use a 0-1 amperes range instead of the 0- 500 ma range. 

Now, with the lamp inserted, the meter indicates a current flow so what greater than 1\2 amp. the instructors are called several trainees to read the meter simultaneously from different positions and record their readings. notice that the reading taken at wide-angle differ considerably from those obtained directly in front of the meter. 

Now, the entire class reads the meter and interpolates the reading between estimated scales division. since the meter scale permit reading between two places directly, the interpolates in the figure of the reading . for examples, the scale division between .6 and .7 are .62, .64 , .66 and .68.