A potentiometer PQ is set up to compare two resistances as shown in the figure. The ammeter A in the circuit reads 1.0 A when two way key K3 is open. The balance point is at a length l1 cm from P when two way key K3 is plugged in between 2 and 1, while the balance point is at a length l2 cm from P when key K3 is plugged in between 3 and 1.
The ratio of two resistances is found to be :
As we learnt in
Meter bridge -
To find the resistance of a given wire using a meter bridge and hence determine the specific resistance of its materials
- wherein
When key is at point (1)
When key is at 3
Option 1)
This option is incorrect
Option 2)
This option is incorrect
Option 3)
This option is incorrect
Option 4)
This option is correct
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