In a metre-bridge when a resistance in the left gap is 2 and unknown resistance in the right gap, the balance length is found to be 40 cm. On shunting the unknown resistance with 2 , the balance length changes by :
(2) 22.5 cm
Balance: PQ= l100-l
2X= 4060 X=3
Shunted: X'= 3 23+2=1.2
21.2= l'100-l' 5(100-l')=3l'
l'= 5008=62.5 cm
change =62.5-40=22.5 cm
Answer: (2)
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