Question

The science laboratory in a school has the following apparatus available in it:

Battery	:	6 V
Rheostat	:	Varies battery voltage from 0 to 6 V
Resistors	:	3 Ω and 6 Ω
Ammeters	:	A1 of range 0 to 5 A; Least count 0.25 A
	:	A2 of range 0 to 3 A; Least count 0.1 A
Voltmeters	:	V1 of range 0 to 10 V; Least count 0.5 V
	:	V2 of range 0 to 5 V; Least count 0.1 V

For the experiment to determine the equivalent resistance of the two given resistors connected in parallel, the best combination would be:
(1) ammeter A₁ and voltmeter V₂
(2) ammeter A₂ and voltmeter V₁
(3) ammeter A₁ and voltmeter V₁
(4) ammeter A₂ and voltmeter V₂

Answer 1

Maximum battery voltage possible in the circuit = 6 V

Total resistance of parallel combination = $2\text{Ω}$

The Maximum current that can flow in the circuit = $\frac{\text{Maximum Voltage}}{\text{Total resistance}}=\frac{6}{2}=3\text{A}$

According to given data, the ammeter A₂ will perfectly suit for the setup, as it has its maximum range equal to the maximum current possible in the circuit and also the minimum least count.

Also, the voltmeter V₁ would be most suitable because it can measure the maximum possible voltage drop across the resistors, whereas the other voltmeter can not.

Hence, the correct answer is option 2.