The following 3 apparatus in parallel are connected across a 100V source:i). a voltametre of resistance 1000 ohm,ii). a combination of resistance in series with an ammetre receding 0.5A &iii). a 100V, 50W lamp.Now find out a) the total current drawn from the source andb) the equivalent resistance of the combination.

Equivalent resistance=3Ω+6Ω=9Ω=3Ω+6Ω=9Ω
Maximum current to be measured=4.5V9Ω=0.5A=4.5V9Ω=0.5A
Maximum voltage to be measured(9Ω)(0.5A)=4.5V(9Ω)(0.5A)=4.5V
AmmeterA2A2and voltmeter(V2)(V2)fulfil these requirements of measuring current and voltage. Apart from this, these two instruments have maximum accuracy due to their smaller least counts(0.05Aand0.1Vrespectively)(0.05Aand0.1Vrespectively).