Answer to Question #295397 in English for Naomi miona

Question

A moving coil instrument has a full scale deflection of 20mA and a resistance of 25ohms , determine the value of the resistor to be used as a,,, shunt to enable the instrument to be used as a 0-20AAmmeter,and multiplier to enable the instrument to be used as a 0-20v voltmeter

Answer 1

(i) The resistance is

r=r_qI_q/I-I_a = 25*20*10^-3/20-20*10^-3 = 0.025Ω.

(ii) The resistance is

r=r_v(V/Vv-1)

r=25(20/25*0.02-1)

r=25(40-1)

r=975Ω.