Question

The following pieces of apparatus are available in a laboratory :
Battery : adjustable from 0 to 6 V
Resistors : `3 Omega` and `6 Omega`
Ammeters : `A_1` of range 0 to 5 A , least count `0.25 A`
`A_2` of range 0 to 3 A , least count `0.1 A`
Voltmeters : `V_1` of range 0 to 10 V , least count `0.5 V`
`v_2` of range 0 to 5 V , least count 0.1 V
For the experiment to find the equivalent resistance of the parallel combination of the two given resistors, which is the best choice ?

Answer 1

Equivalent resistance `= (3 xx 6)/(3 + 6) Omega = 2 Omega`
Maximum current to be measured `= (6 V)/(2 Omega) = 3 A`, Maximum voltage to be measured `(2 Omega)(3 A) = 6 V`
Ammeter `A_2` and voltmeter `V_1` fulfil these requirements. We cannot use voltmeter `V_2` (of range 0 to 5 V) even though its least count is smaller than that of `V_1` as we have to measure upto `6 V`.