Question

A microammeter has as resistance of `100 Omega` and full scale range of `50 muA`. It can be used a voltmeter or as ahigher range ammeter provided a resistance is added to it. Pick the correct range and resistance combinations
50 V range with `10 kOmega` resistance in series
b.`10 V` range with `200 kOmega` resistance in series
c. 5mA rangw with `1Omega` resistance in parallel
`10 mA` range with `1Omega` resistance in parallel

Answer 1

To increase the range of ammeter a parallel resistance (called shunt) is required which is given by
`S=(i_g/(i-i_g))G`
For option c `S=((50xx10^-6)/(95xx10^-50xx10^-60))(100)~~1Omega`
To change it in voltmeter a high resistance `R` is put in series, where `R` is given by `R=V/i_g-G`
For option b.`R=10/(50xx10^-6)-100~~200kOmega`
therefore options b and c are correct.