The following apparatus is available in a laboratory.
Find the best combination of voltmeter and ammeter for finding the equivalent resistance of the resistors in series.
Equivalent resistance = 3 + 6
= 9Ω
Maximum voltage to be measured = 4.5
Maximum current to be measured = 4.5/9
= 0.5 A
These requirements of measuring this current and voltage are fulfilled by ammeter A2 and voltmeter V2 and these two instruments have smaller least counts 0.05 A and 0.1 V so these are more accurate. Hence the best combination of ammeter and voltmeter is A2 and V2.
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