AMMETERS Test Instruments & Measuring Devices Find:    1. accuracy 2. %loading error 3. true current 4. measured current 1. K_A R R_o R_m K_A 2000 2000 400 K_A 0.833  or  83.3% 2. %  loading  error (1 K_A)(100%) %  loading  error (1 0.833)(100%) %  loading  error 16.7% 3. I_o V R_o 20 2000 I_o 0.01A  or  10mA 4. I_w V R_o R_m 20 2000 400 I_w 8.33x10³A  or  8.33mA An ammeter with a full scale I_m can be shunted with a resistor R_SH in order to measure currents in  excess  of  I_m  (Figure  8).   The  reason  for  shunting  an  ammeter  is  to  extend  the  range  of  the ammeter and, thereby, measure currents higher than the original full scale value. ES-14 Page 12 Rev. 0