Answer to Question #13208 in Electric Circuits for abhi
why we cannot decrease the range of an ammeter
Ammeter sensitivity is the amount of current necessary to cause full scale deflection (maximum reading) of the ammeter. The smaller the amount of current, the more "sensitive" the ammeter. For example, an ammeter with a maximum current reading of 1 milliampere would have a sensitivity of 1 milliampere, and be more sensitive than an ammeter with a maximum reading of 1 ampere and a sensitivity of 1 ampere. To decrease the range of an ammeter we need to change it's sensivity, so that's why it is impossible.