An ammeter of resistance `0.80 Omega` can measure current upto 1.0 A. What must be the value of shunt resistance to enable the ammeter to measure current upto 5.0 A ? What is the combined resistance of the ammeter and the shunt?

Explanation

Here `I_g = 1.0 A, I = 5.0 A and R_G = 0.80 Omega`
`:.` Resistance of shunt `r_(s) = (I_(g) cdot R_G)/(I - I_g) = (1.0 xx 0.80)/(5.0 - 1.0) = 0.20 Omega`
Net resistance of the ammeter and the shunt `R = (R_G xx r_s)/(R_G xx r_s) = (0.80 xx 0.20)/(0.80 + 0.20) = 0.16 Omega`.