Question

A milliammeter of range `10 mA` and resistance `9 Omega` is joined in a circuit as shown. The metre gives full-scale deflection for curretn `I` when `A` and `B` are used as its terminals, i.e., current enters at `A` and leaves at `B` (`C` is left isolated). The value if `I` is

A. 100 mA
B. 900 mA
C. `1 A`
D. `1.1 A`

Answer 1

Correct Answer - C

`(I - 10 xx 10^-3) xx 0.1 = (9 + 0.9) xx 10 xx 10^-3`
`I - 10 xx 10^-3 = 990 xx 10^-3`
`I = 1000 xx 10^-3 = 1 A`.