In the circuit shown in figure, the current is to measured. What is the value of the current if the ammeter shown (i) is a galvanometer with a resistance `R_G=60*00Omega`. (ii) is a galvanometer described in (i) but converted to an ammeter by a shunt resistance `r_s=0*02Omega`, (iii) is an ideal ammeter with zero resistance?

Explanation

(b) Resistance of the galvanometer as ammeter is
`(R_(0) r_s)/(R_(G) r_s) = (60Omega xx 0.02 Omega)/((60+0.02))= 0.02 Omega`
Total resistance `R = 0.02Omega + 3Omega = 3.02Omega`
Hence, `I = (3)/(302) = 0.99 A`